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The current study addresses the chemical coprecipitation approach for synthesizing ZnFe 2 O 4 nanoparticles. Zeta potential analyses were employed to investigate the distribution of particle sizes, polydispersity, and stability within these systems. Rietveld refinement patterns unveiled the effective synthesis of the cubic-structured ZnFe 2 O 4 , devoid of any secondary phases. The outcomes showed the significant impact of the modification approach applied on the colloidal stability of the investigated nanoparticles. UV–Vis spectroscopy confirms that the band gap decreases, and absorption increases with doping. The photoluminescence spectroscopy of the samples revealed empty oxygen spaces and cracks in the structure had formed in the lattice. For electrocatalysis, 10 % Ce doped ZnFe 2 O 4 had an oxygen evolution reaction onset potential of 151 mV vs Ag/AgCl to obtain 10 mA/cm2 current density and the lowest Tafel slope of 35 mV/dec. Therefore, the strategic nanostructuring and design of nanomaterials incorporating earth metal-doped metal oxides are necessary to achieve superior electrochemical performance in their respective energy conversion applications. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (gCN) has shown great potential in photocatalysis. Developing suitable cocatalysts is a critical way to enhance gCN's photocatalytic performance. In this paper cobalt–nickel bimetallic phosphide (CoNiP) was used as a cocatalyst to modify gCN. A gCN/CoNiP composite was successfully prepared by a simple hydrothermal method. XRD, XPS, SEM, UV-vis DRS, and PL characterization studies showed that a Schottky junction-like structure was constructed between gCN and CoNiP, which intensified the visible light response, enhanced the charge transfer rate and prohibited the recombination of photogenerated carriers, thus significantly improving gCN photocatalytic activity. Under simulated sunlight, the removal efficiency of methylene blue (10 mg L−1) was 97.8% by 120 min of irradiation, 44.6% higher than that of gCN. The quenching experiment showed that ˙O2−, ˙OH and h+ were the main active species. Based on the above points, the possible mechanism of photocatalysis was deduced. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen evolution is an efficient and clean hydrogen production technology with simple process and high product purity. Searching for inexpensive alternatives to platinum will help popularize proton exchange membrane water electrolysis (PEMWE) technology. However, the alternative catalytic materials are essentially limited by low catalytic efficiency. Herein, we address this challenge through chemically activating cobalt phosphide (CoP) by doping a small amount of atomic palladium. Palladium substitution occurs at the cobalt site of CoP. Theoretical calculations manifest that the phosphorus atoms near the palladium sites exhibit almost zero hydrogen adsorption free energy. The final cobalt phosphide doped with only 2 wt% of palladium shows wonderful HER performance. Specifically, its overpotential at a current density of 10 mA cm−2 is only 37.5 mV in an acidic medium, and the corresponding Tafel slope is 56 mV dec−1. This work provides a reference for preparing high performance non-platinum catalysts. [Display omitted] • We successfully doped Pd atoms into CoP (Pd–CoP@NC) by designing a thermodynamic spontaneous reaction. • Palladium doping greatly improves the hydrogen evolution performance of CoP. • Carbon monoxide poisoning experiment proves that doped Pd atoms are not active sites. • DFT calculations show that phosphorus atoms near the palladium site exhibit almost zero hydrogen adsorption free energy. [ABSTRACT FROM AUTHOR]

Designing composites with rational structure and composition is a promising approach to obtain efficient electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this study, zeolitic imidazolate frameworks-67 (ZIF-67) is employed as a self-sacrificing template to synthesize Co/carbon nanotubes (CNTs) precursor, which is subsequently in-situ nitrided and phosphorized to form cobalt phosphide/nitride/carbon nanotubes (Co 2 P/Co 4 N/CNTs) composite. The realized Co 2 P/Co 4 N composite exhibits heterogeneous nanoparticle microstucture with an average diameter of approximately 10 nm, encapsulated by carbon nanotubes with a porous dodecahedral array. Moreover, there is a well-defined interface between cobalt phosphide, cobalt nitride phases, and carbon nanotubes species. Benefiting from the synergistic effect of Co 4 N and Co 2 P, rich active sites, and high conductivity of CNTs, the composite catalyst demonstrates remarkable HER and OER activities, requiring overpotentials of 228 and 389 mV to support 100 mA cm−2 current density, respectively. This work presents a novel strategy for designing efficient bifunctional catalysts towards HER and OER. [Display omitted] • Co 2 P/Co 4 N/CNTs composite catalyst is prepared by in-situ converting ZIF-67 precursor. • The composite consist of CNTs encapsulated Co 2 P/Co 4 N heterogeneous nanoparticles. • The good interface of Co 2 P, Co 4 N and CNTs is in favor of improving conductivity and activity. • Co 2 P/Co 4 N/CNTs composite need 228 mV overpotential to support 100 mA cm−2 for HER. [ABSTRACT FROM AUTHOR]

Under the gravity of future socio-economic development, the viability of water electrolysis still hinges on the accessibility of stable earth-abundant electrocatalysts and net energy efficiency. This work emphasizes the design and synthesis of two newly developed cobalt(II) complexes, [Co(HL)2(NCS)2] (Comono) and [Co2(L)3(CH3OH)]ClO4 (Codi), with a (N,O)-donor ligand, HL (2-methoxy-6-(((2-methoxyphenyl)imino)methyl)phenol). The study delves into understanding their structural, morphological, magnetic, and charge transport characteristics. Moreover, the study explores the potential of these complexes in catalyzing hydrogen production through heterogeneous electrocatalysis. The X-ray crystal structure of Comono reveals the octahedral geometry of the Co(II) ion, adopting two HL units and two NCS− units. The Codi complex exhibits a doubly-phenoxo-O-bridged (μ1,1) dinuclear complex, forming a typical octahedral geometry for both the Co(II) centres in coupling with three units of L−. Temperature-dependent magnetic susceptibility measurements showed that all of the Co(II) ion in Comono shows a typical paramagnetic behaviour for high spin octahedral Co(II) ions while the Co(II) centres in Codi are coupled with doubly-phenoxo-bridges bearing weak ferromagnetic characteristics at low temperature. Electron transport properties of the Co(II) complex-mediated Schottky device address the superior carrier mobility (μ) for Codi (9.21 × 10−5) over Comono (2.02 × 10−5 m2 v−1 s−1) with respective transit times of 1.70 × 10−9 and 7.77 × 10−9 s. Additionally, electron impedance spectral analysis supports the lower electrical transport resistance of Codi relative to Comono. The heterogeneous electrocatalytic HER activity of Codi and Comono in 0.1 M KOH shows excellent electrocatalytic efficiency in terms of the various electrochemical parameters. Constant potential electrolysis, multi-cycle CVs, and post-HER analysis reveal the pre-catalytic nature of the complexes, which in turn delivers Co3O4 nanoparticles as the active catalysts for efficient hydrogen evolution. [ABSTRACT FROM AUTHOR]

The development of bifunctional, non‐noble metal‐based electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through morphology and electronic engineering is highly attractive for efficient water splitting. Herein, hierarchical nanoarrays consisting of crystalline cobalt phosphide nanorods covered by amorphous Fe‐doped cobalt phosphide nanocuboids (CoP/FeCoPx) are constructed as bifunctional catalysts for both HER and OER. Experimental results and theoretical calculations reveal that the catalysts exhibit balanced dual‐catalytic properties due to simultaneous introduction of Fe doping and phosphorus vacancies, leading to an optimized electronic structure of the CoP/FeCoPx. Furthermore, the hierarchical nanoarrays made of crystalline/amorphous heterostructures significantly enhance the performance of the electrocatalysts. As a result, the CoP/FeCoPx catalyst demonstrates remarkable performance in both HER and OER, with overpotentials of 74 and 237 mV at 10 mA cm−2 in 1 m KOH, respectively, as well as a low cell voltage of 1.53 V at 10 mA cm−2 for alkaline overall water splitting. This work integrates the morphology engineering involving design of hierarchical crystalline/amorphous nanoarrays and the electronic engineering through Fe doping and phosphorus vacancies for efficient water electrolysis. It may open a new route toward rational design and feasible fabrication of high‐performance, multifunctional, non‐noble metal‐based electrocatalysts for energy conversion. [ABSTRACT FROM AUTHOR]

The development of efficient and stable non-precious bifunctional electrocatalysts is of great significance, but it remains a great challenge. Herein, we have constructed Co/CoP@NC heterojunction catalyst loaded with Co and CoP particles on a nitrogen-doped carbon (NC) substrate using the pyrolysis-oxidation-phosphating strategy. The synergistic effect of Co and CoP particles on the NC substrate increases the active specific surface area, accelerates the charge transfer rate, and improves the intrinsic activities of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The Co/CoP@NC catalyst exhibits superior HER and OER performance. Specifically, the overpotentials required for Co/CoP@NC to reach the current density of 10 mA cm−2 are 142 and 186 mV for HER and OER, respectively. This study provides new insights into the design and synthesis of efficient and stable Co-based heterostructure catalysts. [Display omitted] • Co/CoP@NC is prepared by the pyrolysis-oxidation-phosphating strategy. • Co/CoP@NC has a larger specific surface area and faster charge transfer. • The OER performance of Co/CoP@NC is better than commercial Ir/C at 10 mA cm−2. • Only 1.67 V is needed for Co/CoP@NC to drive 10 mA cm−2 for overall water splitting. [ABSTRACT FROM AUTHOR]

The rapid reduction of fossil fuels due to excessive consumption has prompted the development of sustainable energy conversion systems, leading to an increasing energy crisis and environmental concerns. The continuous energy demand motivates researchers to explore new options for energy conversion and water splitting. But, the fabrication of electrocatalysts with low overpotential for water splitting is challenging task. Current study reports the fabrication of rGO-based Dy 2 O 3 composite as an electrocatalyst for water splitting. The rGO-based Dy 2 O 3 was fabricated via a hydrothermal approach. The various physical methods were performed to assess the morphological, vibrational, structural, functional and textual characteristics of synthesized electrocatalysts. In addition, the electrochemical potential of generated materials is evaluated in 1 M KOH electrolyte using Ni foam (NF) serving as conductive material. The electrochemical findings show that rGO-based Dy 2 O 3 composite exhibits a least overpotential of 251 mV at current density (C d) of 10 mA cm−2 and possessing Tafel slope (36 mV dec−1). The Dy 2 O 3 /rGO composite demonstrates stability over a period of 50 h with a minute change in current. The Dy 2 O 3 /rGO composite stands out as a favorable catalyst for OER and future energy conversion applications due to its remarkable electrochemical characteristics. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) over perovskite oxides, upon undergoing a lattice oxygen oxidation mechanism, is strongly oxygen vacancy‐correlated as determined by the oxygen ion diffusivity. Despite substantial efforts having been devoted to tuning the oxygen vacancy concentration in perovskite oxides, the impact of the concomitant altering of oxygen vacancy ordering is often underestimated. In particular, the underlying mechanism of how the ordering and the concentration of oxygen vacancy affect the lattice OER, and how to well balance them still remain inadequately understood. Herein, a series of Sr1−xCaxCo0.5Fe0.5O3−δ with gradually increased oxygen vacancy concentration and ordering are synthesized. Theoretical calculations indicated that a higher oxygen vacancy concentration promoted the lattice oxygen migration, whereas a higher oxygen vacancy ordering impeded it. Particularly, Sr0.5Ca0.5Co0.5Fe0.5O3−δ with a relatively higher oxygen vacancy concentration and a lower ordering displayed the maximum oxygen diffusion rate and the optimal OER activity, affording a current density of 10 mA cm−2 at a quite low overpotential of 310.2 mV, together with a small Tafel slope of 55.87 mV dec−1. This study sheds light on the critical influence of oxygen vacancy configuration on the lattice OER, and paves a compromised avenue to screen and design advanced electrocatalysts for various electrochemical devices. [ABSTRACT FROM AUTHOR]

Designing efficient water splitting electrocatalysts in pH-universal electrolytes is vital yet poses significant challenges. Here, the CoP/MoO 2 heterogeneous interface embedded in porous N-doped carbon (CoP/MoO 2 /NC) was designed by phosphating asphalt enwrapping polyoxometalate-based metal-organic frameworks (POM/ZIF67@asphalt). The CoP/MoO 2 /NC shows excellent performances with low overpotentials of 55, 50, 99 mV for HER and 194, 185, 285 mV for OER at 10mA·cm−2 current density in 1.0 M KOH, 0.5 M H 2 SO 4 , and 1.0 M PBS, respectively. Such superior performance can be attributed to the highly dispersed nanoparticles, heterogeneous interface effect of electron transfer from CoP to MoO 2 , and optimized Gibbs free energy. The long-time stabilities for over 24 h are ensured with negligible decline in all electrolytes, which can be attributed to the excellent stability of CoP/MoO 2 and the corrosion resistance of thin carbon layer. Additionally, in overall water splitting, the CoP/MoO 2 /NC only requires voltages of 1.53 V/1.52 V/1.67 V to gain 10 mA cm−2 in alkaline medium, acidic medium and neutral medium, which exceeded the most reported non-precious catalysts. This work exhibits the excellent pH-universal electrocatalysts with high activity and stability. [Display omitted] • CoP/MoO 2 heterojunction embedded in porous N-doped carbon was prepared by using petroleum pitch as carbon source. • The unique structure of CoP/MoO 2 /NC provided the highly dispersed nanoparticles. • CoP/MoO 2 /NC had excellent catalytic performances toward HER, OER and overall water splitting over a wide pH range. [ABSTRACT FROM AUTHOR]

It is of great significance to design photoelectrodes with high carrier separation and transport efficiency in photocatalytic water separation systems. In this study, we used a simple electrochemical deposition method to regulate the load of co‐catalyst CoP on TiO2 nanorods to improve the photoelectrochemical properties. The photocurrent density of TiO2/CoP (20) photoanode at 1.23 V increases to 1.57 mA/cm2, which is 3.4 times that of original TiO2. Long‐term photoelectrolysis reveals that this electrode has excellent stability. Mechanistic studies support the role of CoP nanoparticles in improving photoelectrochemical property and imply that the excellent photoelectrochemical property of TiO2/CoP photoanode is mainly ascribed to the suppress of surface photogenerated electrons and holes recombination due to the construction of built‐in electric field between TiO2 and CoP. [ABSTRACT FROM AUTHOR]

Hydrogenolysis of polyethylene and hydrogen production processes are considered as the most sustainable routes both for environmental protection and energy generation. However, these processes require the development of high-performance catalysts with improved activity as well as selectivity. Herein, we report the fabrication of bifunctional MoO 3 @RuO 2 heterostructured nanocatalyst by simple and cost-effective facile hydrothermal method. High-surface area of the MoO 3 @RuO 2 nanocatalyst delivers highest selectivity towards tandem catalytic transformation of polyethylene into linear hydrocarbons in high yields (up to 82 wt%). MoO 3 @RuO 2 heterojunctions were also explored for photoelectrocatalytic H 2 evolution reaction, which exhibited enhanced current density of 164 mA/cm2 and the lowest value of tafel slope of 52 mV dec−1 as compared to pure RuO 2 and MoO 3 which affirms its excellent performance. The enhanced activity was observed due to the generated synergistic interaction between RuO 2 and MoO 3 nanostructures which imparts their remarkable performance in catalysis. [Display omitted] • MoO 3 @RuO 2 as highly active nanocatalyst for hydrogenolysis of polyethylene and H 2 production. • Delivers highest selectivity towards tandem catalytic transformation of polyethylene. • Enhanced current density of 164 mA/cm2 and lowest tafel slope of 52 mV dec−1 affirms its excellent PEC performance. • Efficient catalyst for environmental protection as well as energy generation. [ABSTRACT FROM AUTHOR]

Metal phosphides fabricated using metal organic frameworks (MOF) have recently been widely studied in lithium-sulfur (Li–S) battery because of the unique microstructure and electrocatalytic activity. However, the growth of MOF is very rapid and the particle size mainly focuses on micrometer, which severely limits the catalytic effect. Herein, we fabricate nanoscale MOF embedded with carbon nanotube (CNT), owing to the ultra-small CoP (25 nm, denoted as S-CoP) derived from the phosphating of MOF and unique network of CNT, the designed micro-nano structure S-CoP/CNT accelerates the conversion of lithium polysulfides (LiPSs), boosts the precipitation/decomposition processes of lithium sulfide (Li2S) and provides an effective adsorption barrier. Meanwhile, the fabricated S-CoP/CNT separator endows an ultralong dendrite-free Li deposition up to 1714 h. The Li–S battery with S-CoP/CNT modified separator can deliver an initial capacity of 1513.22 mAh g−1 at 0.1 °C, a reversibility capacity of 574.95 mAh g−1 up to 500 cycles at 0.5 °C. The satisfactory performance is also verified at a high sulfur loading of 4.2 mg cm−2 and a favorable initial capacity of 1161.8 mAh g−1 can be maintained. This study provides a facile strategy to fabricate nano metal phosphides derived from MOF for Li–S battery. [ABSTRACT FROM AUTHOR]

The confined growth of ultra-thin and nanometer-sized FeOOH/CoP on the rough pore wall of self-synthesized hierarchically porous Ni foam support show improved OER activity and stability. [Display omitted] Self-supported electrodes, featuring abundant active species and rapid mass transfer, are promising for practical applications in water electrolysis. However, constructing efficient self-supported electrodes with a strong affinity between the catalytic components and the substrate is of great challenge. In this study, by combining the ideas of in-situ construction and space-confined growth, we designed a novel self-supported FeOOH/cobalt phosphide (CoP) heterojunctions grown on a carefully modified commercial Ni foam (NF) with three-dimensional (3D) hierarchically porous Ni skeleton (FeOOH/CoP/3D NF). The specific porous structure of 3D NF directs the confined growth of FeOOH/CoP catalyst into ultra-thin and small-sized nanosheet arrays with abundant edge active sites. The active FeOOH/CoP component is stably anchored on the rough pore wall of 3D NF support, leading to superior stability and improved conductivity. These structural advantages contributed to a highly facilitated oxygen evolution reaction (OER) activity and enhanced durability of the FeOOH/CoP/3D NF electrode. Herein, the FeOOH/CoP/3D NF electrode afforded a low overpotential of 234 mV at 10 mA cm−2 (41 mV smaller than FeOOH/CoP grown on unmodified Ni foam) and high stability for over 90 h, which is among the top reported OER catalysts. Our study provides an effective idea and technique for the construction of active and robust self-supported electrodes for water electrolysis. [ABSTRACT FROM AUTHOR]

A stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction (OER). Here, a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS2 inner core and an amorphous NiFeW(OH)z outer shell is designed and synthesized using in situ electrochemical tuning. The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni0.66Fe0.17W0.17S2@amorphous NiFeW(OH)z nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER. Additionally, the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm−2 at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade−1 in basic media. The Faradaic efficiency of core‐shell Ni0.66Fe0.17W0.17S2@amorphous NiFeW(OH)z is as high as 99.5% for OER. The scanning electron microscope, transmission electron microscope, and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements. Importantly, density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst, optimized the adsorption energy of the OER intermediates, and improved the OER activity. This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites. [ABSTRACT FROM AUTHOR]

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Over the last decades, the transition metal dichalcogenide (TMD) materials have been intensively investigated for hydrogen evolution reaction (HER). Among many TMD catalysts, MoS2 and WS2 are the most efficient materials for HER application because of their advantages including earth abundance, facile synthesis, and high catalytic activities. Herein, a simple and scalable process is introduced which was employed to prepare the nanoflower (NF) heterostructure of MoS2 and WS2 (MoS2/WS2 NF). The superior catalytic activity of the synthesized MoS2/WS2 NF could be contributed by the unique properties of the heterostructure between WS2 and MoS2 materials. Low overpotential (251 mV) at a current density of 10 mA cm−2, small Tafel slope (61 mV dec−1), good conductivity, and superstability are the main properties of the prepared MoS2/WS2 NF. This work presents a new facile novel to prepare efficient catalysts which could be great candidates for HER and electrocatalytic application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Advantages of the Co 2 P/Co heterostructures are demonstrated by DFT calculations. • Hierarchical porous Co 2 P/Co heterostructures on CC are elaborately constructed. • Typical Co 2 P/Co/CC shows excellent HER and OER performance and high stablility. • The Co 2 P/Co/CC||Co 2 P/Co/CC cell reaches 10 mA/cm2 at 1.54 V with ultralong lifetime. • Improved intrinsic activity and highly exposed active sites are the main reasons. Constructing heterostructured electrocatalysts has proven effective in enhancing intrinsic catalytic activity. Herein, under guidance of theoretical calculations, hierarchical porous quasi-hexagonal Co 2 P nanosheets/Co heterostructures supported on carbon cloth (Co 2 P/Co/CC) with a high surface area were rationally designed and elaborately constructed through electroless Co plating, electrochemical oxidation, and phosphidation process, which showed significant electrocatalytic performance toward water electrolysis. Specifically, theoretical calculations revealed that the Co 2 P/Co heterostructure adjusted the electronic structure of Co 2 P and Co, reducing the energy barrier for target reactions and thereby boosting electrocatalytic activities for the hydrogen evolution reaction (HER). Notably, the typical Co 2 P/Co/CC catalyst demonstrated impressive HER performance, with low overpotentials of only 52 and 48 mV to achieve a current density of 10 mA/cm2 in 0.5 M H 2 SO 4 and 1.0 M KOH solutions, respectively. The remarkable electrocatalytic performance of the catalyst can be attributed to the improved intrinsic activity resulting from the Co 2 P/Co heterostructures and the highly exposed active sites provided by the hierarchical porous structures. Furthermore, the Co 2 P/Co/CC catalyst exhibited excellent oxygen evolution reaction (OER) performance in alkaline electrolyte, requiring a low overpotential of only 306 mV to achieve a current density of 100 mA/cm2. Additionally, a two-electrode electrolyzer assembled with the Co 2 P/Co/CC electrodes achieved a current density of 10 mA/cm2 at a low cell voltage of 1.54 V and demonstrated excellent long-term stability. This work presents a novel and feasible strategy for constructing hierarchical heterostructured electrocatalysts that enable efficient water electrolysis. By combining rational design and theoretical guidance, our approach offers promising prospects for advancing the field of electrocatalysis and facilitating sustainable energy conversion. [ABSTRACT FROM AUTHOR]

Hydrogen presents itself as a promising alternative to the effort for meeting the need for high energy density. Hydrogen has enormous potential to address the issues of climate change and energy sustainability since it is a clean, sustainable energy source. Water splitting is one of the most promising approaches among the several technologies investigated for producing hydrogen. Water splitting provides an effective and clean way to produce hydrogen through the use of electrochemical processes. One particularly notable electrocatalyst in the field of water splitting is cobalt phosphide (CoP). CoP catalytic qualities are superior to those of platinum on carbon (Pt/C), the traditional standard that is both costly and scarce. CoP is an appealing choice for industrial-scale hydrogen generation because of its noteworthy performance attributes at a reasonable price. Its capacity to transform clean energy technologies is demonstrated by its effectiveness in promoting the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In the context of water splitting, this study explores the many benefits of CoP. Beyond its excellent performance and cost-effectiveness, CoP offers design and application diversity, creating opportunities for more electrocatalysis innovation and optimization. In the review, CoP metal-organic frameworks (MOFs) are highlighted for their exceptional porosity, high surface area, and tunable chemical properties, offering promising advantages for applications in gas storage, catalysis, and sensing. This study intends to support ongoing efforts towards a clean and green energy future by clarifying the special advantages of CoP and its role in enhancing water splitting technology. [Display omitted] • Evaluating sustainable hydrogen production from renewable sources. • Cobalt Phosphide (CoP) and its hybrids show potential as catalysts for water splitting. • A review article outlines current research on Cobalt Phosphide catalysts. • Focusing on synthesis enhancements and advancements in catalytic mechanisms of CoP. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and electrocatalytic performance of the cobalt(III) complex [Co3(μ1,1,1‐O)(μ1,3‐CH3CO2)(L)3]2(DMF)3 (Cotri), featuring a double deprotonated (N,O)‐donor ligand (L2‐), where the protonated form of it (H2L) is 2,2′‐(hydrazine‐1,2‐diylidenebis(ethan‐1‐yl‐1‐ylidene))diphenol. The X‐ray structure reveals a trinuclear cobalt cluster formed with three cobalt(III) centers interlinking through oxido (μ1,1,1‐O) and acetato (μ1,3‐O2CCH3) bridges in coupling with bis‐congregator‐type chelating ligands. Cotri adopts cobalt centers of octahedral and trigonal bipyramidal coordination geometries and bears a dominant Co(2)...H(DMF) agostic interactions appraised by lattice dimethyl formamide (DMF) molecules. Further, Cotri shows promising heterogeneous electrocatalytic hydrogen evolution activity in 1 M KOH, with an overpotential of 441 mV to achieve 10 mA/cm2 current density. Tafel slope analysis suggests the Volmer–Heyrovsky step as the rate‐determining step. The number of active sites and TOF for Cotri were estimated at 4.010 × 10−8 mol and 0.2467 s−1, respectively, ensuring its excellent hydrogen generation activity. Stability assessments through controlled potential electrolysis (CPE) and cyclic voltammetry (CV) for multiple cycles addressed the transformation of Cotri to Co2O3 nanoparticles, which turned out to be a more active Co2O3 electrocatalyst. The morphology and particle size of the in situ developed Co2O3 active catalyst under the electrochemical conditions attributes to the superior hydrogen evolution activity. [ABSTRACT FROM AUTHOR]

The catalytic performance of spinel oxide NiCo2O4 for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was investigated. It shows that NiCo2O4 synthesized via hydrothermal treatment at 90 ℃ followed by calcination at 350 ℃ exhibits excellent catalytic activity. Furthermore, Fe-doped MnO2 (marked as Fe-M) was introduced as a modifier to further improve the performance of NiCo2O4. As expected, the 20% Fe-M hybrid catalyst (NiCo2O4 modified with 20 wt% Fe-M) displays the best ORR and OER catalytic activity. This is evidenced by its high OER current density of 265 mA cm−2, high ORR current density of 220 mA cm−2, low OER Tafel slope of 119 mV dec−1, low ORR Tafel slope of 167 mV dec−1. These exceptional results can be attributed to the synergistic effect between NiCo2O4 and Fe-M. Based on synergistic effect, the 20% Fe-M hybrid catalyst exhibits the best catalytic activity for oxygen evolution reaction and oxygen reduction reaction. [ABSTRACT FROM AUTHOR]

Possible conversion mechanism of S on the surface of N -CoP. [Display omitted] • Theoretical simulation results uncover that an introduced N element into CoP could form a shorter Co-N bond, create a higher charge number of the Co central atom, bring new defect levels, and induce the Co 3d band closer to Fermi level. • Further atomic level analysis revealed that N -CoP could form shorter Co-S bonds with sulfur species and simultaneously weaken the S S bridged bond of Li 2 S 4 and Li-S bond of Li 2 S. • The doping of CoP eventually facilitates the polysulfides conversion reaction in the discharge process and the Li 2 S oxidation in the charge process. Lithium polysulfide (LiPSs) shuttle effect and difficulties with Li 2 S oxidation are hinder the marketization of lithium-sulfur batteries. We suggest using a bidirectional catalyst in the sulfur host to solve these problems. We produced a nitrogen-doped cobalt phosphide (N -CoP@NC) as a sulfur carrier in this work. The introduction of nitrogen into cobalt phosphide enhances the electron transmission speed and forms shorter Co-N bonds. As a result, new defect energy levels are introduced, leading to an increase in the charge number of Co central atoms, which abate the Li-S and S S bonds in Li 2 S and Li 2 S 4 , thereby promoting the oxidation of Li 2 S during charging, as well as the alteration process of LiPSs during charge and discharge. Additionally, the crystal flaws that result in increased Co-S bond formation help to boost polysulfides' adsorption ability. The Li-S batteries shows outstanding cyclability when paired with this electrocatalyst, demonstrating a minimal capacity degradation rate of only 0.07 % per cycle over 500 cycles at a rate of 0.5C. As a result, incorporating anion doping in the host emerges as a promising method for crafting materials tailored for Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo, W doped Co 2 P/NF electrodes were designed for HER and GOR. • High catalytic efficiencies for HER, GOR were fulfilled. • The surface evolved CoO 2 was the genuine catalytic species for GOR. • H 2 and formate were coproduced by energy-saving glycerol electrolysis. H 2 and formate are important energy carriers in fuel-cells and feedstocks in chemical industry. The hydrogen evolution reaction (HER) coupling with electro-oxidative cleavage of thermodynamically favorable polyols is a promising way to coproduce H 2 and formate via electrochemical means, highly active catalysts for HER and electrooxidative cleavage of polycols are the key to achieve such a goal. Herein, molybdenum (Mo), tungsten (W) doped cobalt phosphides (Co 2 P) deposited onto nickel foam (NF) substrate, denoted as Mo-Co 2 P/NF and W-Co 2 P/NF, respectively, were investigated as catalytic electrodes for HER and electrochemical glycerol oxidation reaction (GOR) to yield H 2 and formate. The W-Co 2 P/NF electrode exhibited low overpotential (η) of 113 mV to attain a current density (J) of −100 mA cm−2 for HER, while the Mo-Co 2 P/NF electrode demonstrated high GOR efficiency for selective production of formate. In situ Raman and infrared spectroscopic characterizations revealed that the evolved CoO 2 from Co 2 P is the genuine catalytic sites for GOR. The asymmetric electrolyzer based on W-Co 2 P/NF cathode and Mo-Co 2 P/NF anode delivered a J = 100 mA cm−2 at 1.8 V voltage for glycerol electrolysis, which led to 18.2 % reduced electricity consumption relative to water electrolysis. This work highlights the potential of heteroelement doped phosphide in catalytic performances for HER and GOR, and opens up new avenue to coproduce more widespread commodity chemicals via gentle and sustainable electrocatalytic means. [ABSTRACT FROM AUTHOR]

Recent development and expansion in electrochemical water splitting processes have driven the research community to explore an efficient, economical and eco-friendly electrocatalyst. Within this domain, the electrocatalytic oxygen evolution reaction (OER) presents a notable challenge due to its inherent inefficiency arising from a sluggish four-electron transfer process. In the present study, we investigated a hydrothermal technique for synthesizing an electrocatalyst featuring MnO-embedded CoFe2O4 spinel oxide, which is firmly anchored onto a nickel foam (NF) substrate. The electrocatalyst demonstrated impressive performance, exhibiting exceptional stability over an 82-h endurance test. A significantly smaller overpotential was required for OER, achieving a notable decrease of 179 mV. Furthermore, it displayed a Tafel value of approximately 68 mV dec−1 at current density of 10 mA cm−2 for OER, underscoring its exceptional electrocatalytic performance. In light of these compelling findings, the current research has introduced a feasible, environmentally friendly, and potentially high-impact strategy towards the development of cost-effective transition metal-based catalysts, highly suitable for use as electrodes in electrochemical water splitting applications. [ABSTRACT FROM AUTHOR]

CoP and N, O, P triple-doped carbon composites were prepared by low-temperature tandem reaction using MOF as a self-sacrificial template, and their lithium storage properties and mechanisms were investigated. [Display omitted] • The formation of dispersed cubic structure facilitates electrolyte penetration and Li+ diffusion. • Heteroatoms doping adjusts the local electric field of the anode improving the reactivity of the material. • Transformation of the mechanism of CoP anode before and after cycling was confirmed by ex-situ techniques. • Theoretical calculations demonstrate the synergistic effect between the co-doped carbon layer and CoP. Cobalt phosphide (CoP) with high theoretical capacity as well as ceramic-like and metal-like properties is considered as a promising anode for lithium-ion batteries (LIBs). However, the large volume change and sluggish kinetic response limit its practical application. The optimization of composition, structural control and performance regulation of CoP electrodes can be achieved by the bottom-up assembly technique of metal–organic frameworks (MOFs). Due to the effective electronic regulation and lithiophilicity brought by the multiple heteroatoms doping and the synergistic effect of the unique structure derived from MOFs, the N, O, P triple-doped carbon and CoP composites (ZCP@NOP) exhibited excellent rate capability (554.61 mAh g−1 at 2 A g−1) and cycling stability (806.7 mAh g−1 after 500 cycles at 0.5 A g−1). The essence and evolution of lithium storage mechanism in CoP electrodes are also confirmed by the ex-situ techniques. The synergistic benefits of heteroatom co-doping carbon and cobalt phosphide, such as the decrease of the diffusion energy barrier of Li-ions and the optimization of electronic structures, are highlighted in theoretical calculations. In conclusion, new thoughts and ideas for the creation of future battery anode are provided by the combination of the N, O, P co-doping and the adaptable structural adjustment technique. [ABSTRACT FROM AUTHOR]

Facile preparation of low-cost electrocatalysts for an efficient oxygen evolution reaction (OER) is significant but remains a big challenge. Herein, a novel and facile strategy for transforming intrinsic non-stoichiometric ultrathin Co5(O9.48H8.52)NO3 nanosheets into oxygen-vacancy enriched Co3O4/CoOOH heterostructure nanosheets for an efficient OER was developed. The as-synthesized Co3O4/CoOOH heterostructure nanosheets displayed excellent OER performances, showing an extremely low overpotential of 260 mV at a current density of 10 mA cm−2, a relatively small Tafel slope of 52 mV dec−1, and a long-term durability of at least 20 h. This work provides a new way for the production of oxygen vacancies on metal (oxy)hydroxide nanosheets through electric-field assisted in situ transformation of non-stoichiometric metal oxyhydroxide nanosheets. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) are considered promising energy storge systems because of their outstanding power density, fast charge and discharge rate and long-term cycling stability. The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors. As the battery-type materials, transition metal phosphides (TMPs) possess high theoretical specific capacity, good electrical conductivity and superior structural stability, which have been extensively studied to be electrode materials for supercapacitors. In this review, we summarize the up-to-date progress on TMPs materials from diversified synthetic methods, diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors. In the end, we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.

In response to the escalating environmental impact of fossil fuels, there's a growing demand for clean energy solutions, particularly efficient metal-air batteries. Metal-air batteries are promising for energy storage, boasting abundant materials and low cost. However, their efficiency is hindered by slow oxygen reduction and evolution reactions. Synthesizing effective and stable oxygen electrocatalysts is crucial for enhancing battery performance. Here, this work used a simple solvothermal method to synthesize Iron–Cobalt metal-organic framework (FeCo-MOF), Manganese–Iron–Cobalt metal-organic framework (MnFeCo-MOF), and their composites with (1, 3, and 5) wt% rGO and characterized via using XRD, SEM, FTIR, and Raman spectroscopy. Electrochemical testing was conducted in 1 M KOH solution for both OER and ORR. The 3 wt% rGO MnFeCo-MOF shown the lowest overpotential of 54 mV at 10 mA/cm2 and the lowest Tafel slope of 63.4 mV/dec, with highest current density of 79.42 mA/cm2 at 25 mV/s scan rate for OER indicating excellent electrocatalytic activity superior to already reported in literature due to synergistic effect of Mn, Fe, Co, and rGO facilitating rapid electron transfer and more active sites. The 3 wt% rGO MnFeCo-MOF exhibited the halfwave potential of 0.74 V for ORR showing excellent activity comparable to commercial catalysts Pt/C. The lower potential gap ΔE 0.66 V from the overall combined plot of OER/ORR shows efficient and stable bifunctional activity of the 3 wt% rGO MnFeCo-MOF. These exceptional electrocatalytic properties pave the way for future advancements in metal-air batteries. [Display omitted] • FeCo-MOF, MnFeCo-MOF, and their composites with rGO were synthesized solvothermaly at 120 °C. • 3 wt% rGO MnFeCo-MOF showed lowest TAFEL slope 63.4 mV/dec and overpotential of 54 mV at 10 mA/cm2 for OER. • 3 wt% rGO MnFeCo-MOF for ORR has a halfwave potential of 0.74 V. • Exhibited excellent stability studied via chronopotentiometry experiment. • Synergic effect among rGO and Mn, Fe, Co MOF active sites. [ABSTRACT FROM AUTHOR]

High-entropy materials (High-entropy Materials, HEMs) as a derivative of high-entropy alloys (High-Entropy Alloys, HEAs), have become potential oxygen evolution reaction (Oxygen Evolution Reaction, OER) catalytic materials in recent years. High entropy materials have many attractive properties due to their unique polyatomic structure. This study presents a novel synthesis strategy to successfully grow high-entropy sulfides in situ on the surface of high-entropy alloys by a combination of alkali etching and hydrothermal methods. The experimental results demonstrate that the prepared high-entropy sulfide electrode shows excellent catalytic performance for the OER in alkaline electrolytes. It has a lower overpotential compared to the original high-entropy alloy electrode. Additionally, it exhibits better reaction kinetics. In 1 M KOH electrolyte, only 362 mV of overpotential was required to achieve a current density of 20 mA·cm−2 with a Tafel slope of 120 mV·dec−1. The enhanced catalytic activity of the high-entropy sulfide electrode is due to the abundant presence of catalytic active sites. Additionally, the electrode benefits from reduced charge transfer impedance. The synergize of multiple metal elements also plays a significant role in its superior performance. This research demonstrates the potential value of high-entropy sulfide electrodes in the field of electrocatalytic oxygen evolution reaction. The high-entropy sulfide with excellent electrocatalytic OER activity and stability in alkaline media which prepared by hydrothermally sulfiding high-entropy alloy electrodes after alkali etching. The electrode requires only an overpotential of 362 mV to reach a current density of 20 mA cm−2, accompanied by a Tafel slope of 120 mV∙dec−1, and maintains its catalytic activity in 1 M KOH for at least 10 h. This work provides a new idea for the preparation of high-entropy materials mainly composed of non-precious metals, which can enhance the application potential of non-precious metal OER catalysts. [Display omitted] • A novel high-entropy sulfide electrocatalysts base on high-entropy alloy has been synthesized. • High-entropy catalyst with unique structures can be obtained by applying an alkali etching treatment. • High-entropy sulfide electrocatalysts exhibits a nano-needle-like morphology feature. • This work shows the potential of applying HEAs in the area of electrocatalytic oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Transition metal phosphides (TMPs) have attracted extensive interest to catalyze the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). However, the development of TMPs with high conductivity is a great challenge. Herein, we report hybrids of cobalt phosphide (CoP) and copper phosphide (CuP) strongly coupled with ZIF-67 derived carbon as bifunctional ORR/OER electrocatalysts (CoP/CuP@NC). The as-prepared CoP/CuP@NC catalysts exhibit delightful activity and stability toward the ORR (E1/2 = 0.86 V) and the OER (E10 = 1.61 V). Moreover, the assembled Zn-air battery exhibits a small charge-discharge voltage gap and excellent stability. These remarkable electrocatalytic capabilities stem from the combined impact of active CoP/CuP components and the structural framework derived from ZIF-derived materials. This work provides a meaningful strategy for constructing high-performance bifunctional electrocatalysts for commercial Zn-air batteries. [ABSTRACT FROM AUTHOR]

Materials containing cobalt phosphide nanoparticles are among the most promising electrocatalysts for the hydrogen evolution reaction in terms of compromise between activity, cost, and durability. A simple and effective approach to fabricating a nanocomposite of graphene–phosphorene structures decorated with CoP nanoparticles 2–5 nm in size is proposed. The nanocomposite was fabricated by the electrochemical exfoliation of black phosphorus followed by the solvothermal synthesis. The synthesis was carried out in the presence of few-layer graphene structures doped with nitrogen atoms in the solution containing Co2+ ions. The electrocatalyst exhibited high activity and stability towards hydrogen evolution reaction in the acidic medium. In order to achieve a current density of 10 mA cm–2, an overpotential of ~220 mV was required, and the Tafel slope was ~63 mV dec–1. It is suggested that this result is due to both the synergistic effect of the interaction between graphene and phosphorene structures and the electrocatalytic activity of CoP nanoparticles, which are located at the edges of phosphorene structures. [ABSTRACT FROM AUTHOR]

Developing efficient and economical electrocatalysts for hydrogen evolution reaction (HER) over a broad pH range has received considerable attention. In this work, we prepared multi-dimensional MoS 2 /S-CoP heterojunction catalysts by utilizing the carbon clothes supported ZIF-67 array as templates combining with Mo-ion exchange and high-temperature phosphorization-sulfidation strategy. The introduction of MoS 2 into S-CoP results in electron redistribution and the formation of a distinctive space charge region at the two-phase contact interface, thereby effectively tuning surface properties, enhancing electron conductivity, and improving electrocatalytic activity. According to Density Functional Theory (DFT) calculations, the introduction of MoS 2 is advantageous for the adsorption and desorption of H*, resulting in the value of ΔG H* very close to zero. Furthermore, the adsorbed water molecules are more readily activated, rendering the ΔG H2O-dis decrease, thus significantly promoting HER activity. These features contribute to robust HER electrocatalytic performance in a wide pH range and even in seawater, which is also beneficial for industrial applications. In particular, MoS 2 /S-CoP exhibits superior HER performance in alkaline seawater, requiring only 197 and 228 mV to reach the current densities of 100 and 200 mA cm-2, respectively. This study offers novel perspectives on high-performance heterostructures for HER electrocatalysts in alkaline seawater environments. [ABSTRACT FROM AUTHOR]

New heteroleptic dppe appended Co(III)-dithiocarbamate (dtc) complex cations with compositions [Co(S2CNEt2)2(dppe)](PF6) (Co-Et), [Co(S2CNPri2)2(dppe)](PF6) (Co-Pr) and [Co(S2CNBun2)2(dppe)](PF6) (Co-Bu) have been synthesized and characterized by microanalysis, spectroscopic methods and crystallographic analysis. The single crystal X-ray diffraction results indicated that in all three complexes, the coordination environment around Co(III) is distorted octahedral and Co(III) is coordinated to four sulfur centers of the two dtc ligands and the two phosphorus centers of the dppe ligand. These complexes serve as precursors to yield cobalt sulfide/cobalt phosphide nano-composites dCo-Et, dCo-Pr and dCo-Bu by solvothermal decomposition of Co-Et, Co-Pr and Co-Bu, respectively. The decomposed materials have been characterized by PXRD and SEM-EDAX and explored as potential electrocatalysts for both oxygen evolution and hydrogen evolution reactions in basic and acidic media, respectively. Catalytic activity is dependent on the precursor complex and best OER and HER activities are observed for dCo-Bu with an η10 of 230 mV and a Tafel slope of 192.11 mV dec−1 for the OER and an η10 of 470 mV and a Tafel slope of 126.21 mV dec−1 for the HER. [ABSTRACT FROM AUTHOR]

Ammonia borane (AB) has emerged as a promising chemical hydrogen storage material. The development of efficient, stable, and cost‐effective catalysts for AB hydrolysis is the key to achieving hydrogen energy economy. Here, cobalt phosphide (CoP) is used to anchor single‐atom Pt species, acting as robust catalysts for hydrogen generation from AB hydrolysis. Thanks to the high Pt utilization and the synergy between CoP and Pt species, the optimized Pt/CoP‐100 catalyst exhibits an unprecedented hydrogen generation rate, giving a record turnover frequency (TOF) value of 39911 molH2molPt−1min−1${\mathrm{mo}}{{{\mathrm{l}}}_{{{{\mathrm{H}}}_{\mathrm{2}}}}}{\mathrm{\ mo}}{{{\mathrm{l}}}_{{\mathrm{Pt}}}}^{{\mathrm{ - 1}}}{\mathrm{\ mi}}{{{\mathrm{n}}}^{{\mathrm{ - 1}}}}$ and turnover number of 2926829 molH2molPt−1${\mathrm{mo}}{{{\mathrm{l}}}_{{{{\mathrm{H}}}_{\mathrm{2}}}}}{\mathrm{\ mo}}{{{\mathrm{l}}}_{{\mathrm{Pt}}}}^{{\mathrm{ - 1}}}$ at room temperature. These metrics surpass those of all existing state‐of‐the‐art supported metal catalysts by an order of magnitude. Density functional theory calculations reveal that the integration of single‐atom Pt onto the CoP substrate significantly enhances adsorption and dissociation processes for both water and AB molecules, thereby facilitating hydrogen production from AB hydrolysis. Interestingly, the TOF value is further elevated to 54878 molH2molPt−1min−1${\mathrm{mo}}{{{\mathrm{l}}}_{{{{\mathrm{H}}}_{\mathrm{2}}}}}{\mathrm{\ mo}}{{{\mathrm{l}}}_{{\mathrm{Pt}}}}^{{\mathrm{ - 1}}}{\mathrm{\ mi}}{{{\mathrm{n}}}^{{\mathrm{ - 1}}}}$ under UV–vis light irradiation, which can be attributed to the efficient separation and mobility of photogenerated carriers at the Pt‐CoP interface. The findings underscore the effectiveness of CoP as a support for single‐atom metals in hydrogen production, offering insights for designing high‐performance catalysts for chemical hydrogen storage. [ABSTRACT FROM AUTHOR]

Cobalt phosphides have been investigated as potentially useful electrocatalysts for accelerating hydrogen evolution. Cobalt phosphide electrocatalysts are synthesized in a single step at varied phosphating temperatures (350, 400, 450 °C) via the gas phase approach. Synthesized at a phosphating temperature of 350 °C, Co2P (CP‐350) transforms into a mixed phase that contains both Co2P and CoP (CP‐400 and CP‐450) as the phosphating temperature goes up which is confirmed by XRD. CP‐350, CP‐400, and CP‐450 exhibited overpotentials of 181, 270, and 293 mV respectively with Tafel slopes of 112, 146, and 175 mV/dec. In contrast to CP‐400 and CP‐450, CP‐350 revealed superior hydrogen evolution reaction (HER) performance and stability for up to 12 h due to its pure phase (Co2P), high surface area (151 m2/g), and high electrochemical surface area (7.02 cm2) with low charge transfer resistance. According to our work, changing the phase and active surface area of transition metal phosphide catalysts can greatly increase their HER catalytic efficiency. [ABSTRACT FROM AUTHOR]

Efficient and stable oxygen evolution reaction (OER) electrocatalysts are essential for improving the overall efficiency of water electrolyzers. Iron-doped cobalt phosphide (CoFeP) nanowires are prepared via a one-step solvothermal process using a cobalt metal--organic framework (Co MOF), P4 and dissolved Fe2+. The ion-exchange between Fe2+ and the Co MOF occurs first, and then phosphides are formed. CoFeP exhibits the Co2P phase, and there exists an electronic interaction between Co and Fe. When supported on nickel foam (NF) to catalyze the OER in alkaline solutions, CoFeP/NF exhibits an overpotential of 240 mV at a 10 mA cm-2 OER current density, which is much lower than that of Co2P/NF. Kinetic analyses indicate that the lattice oxygen oxidation mechanism occurs at the CoFeP/NF surface, whereas the adsorbate evolution mechanism dominates at the Co2P/NF surface. The change in the mechanistic pathway is due to the increased acidity of the Co4+ site in CoFeP, which favors the decoupled proton--electron transfer process. Lower apparent activation energy, charge transfer resistance and Tafel slope values, and higher electron rate constants are observed on the CoFeP/NF surface, and the charge redistribution induced by Fe during the OER process alters the adsorption energy of the hydroxyl groups at the Co sites, leading to more facile OER kinetics, as proved by density functional theory calculations. CoFeP/ NF shows good long-term durability in alkaline solutions, and the conversion of surface phosphides to oxides and (oxy)hydroxides is observed. [ABSTRACT FROM AUTHOR]

Interfacial oxygen vacancy modified CoP electron bridge could availably expedite charge transfer in BiO 1- x Cl/g-C 3 N 4 Z-scheme heterojunction, thereby achieving the high-efficiency photocatalytic CO 2 reduction coupled with tetracycline oxidation in one system. [Display omitted] • Superficial OVs played a pivotal role in enhancing the electron mobility of CoP electron bridge. • OVs-assisted CoP electron-bridge reduced the interfacial migration resistance of carriers. • OVs-assisted CoP electron-bridge accelerated carrier transfer of BiO 1− x Cl/g-C 3 N 4 heterojunction. • A coupled reaction system was structured by coupling CO 2 reduction with TC degradation. • Coupled reaction system actualized the full utilization of charges. Although great progress has been made with respect to electron bridges, the electron mobility of the state-of-the-art electron bridges is far from satisfactory because of weak electrical conductivity. To overcome the above issue, cobalt phosphide (CoP), as a model electron bridge, was modified by superficial oxygen vacancies (OVs) and embedded into a defective bismuth oxychloride/carbon nitride (BiO 1- x Cl/g-C 3 N 4) Z-scheme heterojunction to obtain atomic-level insights into the effect of surface OVs on CoP electron bridges. Compared to BiO 1- x Cl/g-C 3 N 4 and bismuth oxychloride/cobalt phosphide/carbon nitride (BiOCl/CoP/g-C 3 N 4) composites, the defective bismuth oxychloride/cobalt phosphide/carbon nitride (BiO 1- x Cl/CoP/g-C 3 N 4) heterojunction exhibited remarkable photocatalytic redox performance, indicating that the surface OVs-assisted CoP electron bridge effectively boosted electrical conductivity and yielded ultrafast electron transfer rates. The theoretical and experimental results demonstrate that the surface OVs play a critical role in improving the electrical conductivity of the CoP electron bridge, thereby accelerating electron mobility. This research provides insights into interfacial OVs-modified transition metal phosphide (TMP) electron bridges and their potential application in heterojunctions for energy crisis mitigation and environmental remediation. [ABSTRACT FROM AUTHOR]

Enhancing catalytic activity through modulating the interaction between N-doped carbon and metal phosphides clusters is an effective approach. Herein, the electronic structure modulation of CoP2 supported N-modified carbon (CoP2/NC) has been designed and prepared as efficient electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Notably, CoP2/NC-1 catalyst exhibits impressive performance in alkaline media, with an ORR half-wave potential of 0.84 V, as well as OER and HER overpotentials of 290 and 129 mV (at 10 mA·cm−2), respectively. In addition, CoP2/NC-1 produces a power density as high as 172.9 mW·cm−2, and excellent reversibility of 100 h at 20 mA·cm−2 in home-made Zn-air batteries. The experimental results demonstrate that the synergistic interactions between N modified carbon substrate and CoP2 material significantly enhance the kinetics of ORR, OER, and HER. Density functional theory (DFT) calculations reveal the strong electrons redistribution of CoP2 induced by high-density N atoms at the interface, thus optimizing the key intermediates and significantly lower the energy barrier of reactions. These electronic adjustments of CoP2 greatly enhance its kinetics of ORR/OER/HER, leading to faster reactions. This study provides profound insights into the specific modification of CoP2 by N-doped carbon, enabling the construction of efficient catalysts. [ABSTRACT FROM AUTHOR]

Gas-liquid countercurrent poses a key challenge in achieving a balance between rapid gas discharge and stable liquid supply for high-performance oxygen evolution reaction (OER). Prior research has predominantly concentrated on enhancing the intrinsic activity of catalysts, ignoring the effect of electrode microstructure. Herein, a CoNi 1 –P/O@NF electrode is developed, featuring numerous microwells, cracks, and oxygen vacancies, to enhance the synergistical gas-liquid transport and OER performance. Experimental and simulation findings demonstrate that the existence of microwells and cracks facilitates the separate-path transport of gas and liquid, resulting in reduced mass transfer resistance and rapid bubble growth. Resulting from these characteristics, the overpotential is only 214 mV at a current density of 10 mA cm−2, which is lower than that of commercial IrO 2 (284 mV), indicating an excellent OER performance. This work can contribute to further development of highly efficient OER electrodes by emphasizing the significance of hierarchical microstructure and gas-liquid transport. [Display omitted] • The CoNi x -P/O@NF OER electrode with hierarchical pore structure was constructed. • Hierarchical pore structures promote the separate-path transport of gas and liquid. • Abundant mesopores and defects facilitate the exposure of active sites. • The heterogeneous interfaces improve charge transfer and reactant adsorption. • The overpotential (214 mV at 10 mA cm−2) is lower than commercial IrO 2 (284 mV). [ABSTRACT FROM AUTHOR]

The design and construction of heterogeneous interface is an effective strategy to enhance the performance of non-precious metal catalysts for electrolytic water splitting. Herein, a facile nanostructure of porous cobalt phosphide/ferroferric oxide (Co–P/Fe 3 O 4) composite film on nickel foam (Co–P/Fe 3 O 4 @NF) is designed and prepared by a one-step electrodeposition. The abundant heterogeneous interface of Co–P/Fe 3 O 4 produces and exposes highly active catalytic sites. Meanwhile, the appropriate interaction between cobalt phosphide and Fe 3 O 4 and the close contact between Co–P/Fe 3 O 4 film and NF promote rapid electron transfer in catalytic process. Due to the catalyst being well-designed, the self-supported Co–P/Fe 3 O 4 @NF bifunctional electrodes exhibit outstanding performances with only needing overpotentials of 132.8 mV and 343.0 mV for hydrogen evolution reaction and oxygen evolution reaction, respectively, to drive 20 mA cm−2 in 1.0 M KOH. Additionally, the alkaline electrolyzer assembled by Co–P/Fe 3 O 4 @NF can achieve 10 mA cm−2 at a low cell voltage of 1.686 V. Even better, the electrolyzer can operate continuously over 40 h with nearly 100% Faraday efficiency and can also be powered by commercial solar cells in general outdoor environments. Porous Co–P/Fe 3 O 4 composite film on NF is prepared by one-step electrodeposition and shows perfect catalytic activity toward both OER and HER. [Display omitted] • Co–P/Fe 3 O 4 @NF is designed and prepared by a one-step electrodeposition. • The Co–P/Fe 3 O 4 @NF exhibits perfect catalytic activity toward both HER and OER. • The prefect activity is ascribed to abundant heterogeneous interface in Co–P/Fe 3 O 4. [ABSTRACT FROM AUTHOR]

In this study, cobalt phosphide (CoP 2) was synthesized onto a Nickel foam (NF) support via phosphorylation under an N 2 atmosphere. The resulting material was then coated with tetrahydroxyquinone (THQ), a conjugated microporous polymer, using a hydrothermal method. The as-synthesized CoP 2 /THQ@NF showed remarkable electrocatalytic performance for the hydrogen evolution reaction and excellent durability in acidic electrolytes. This was attributed to the synergistic effect of the NF support, CoP 2 , and THQ, which led to a modified electronic structure of CoP 2 and a high electron transfer rate of THQ. A low overpotential of 137 mV was required in a 0.5 M H 2 SO 4 solution to achieve a current density of 10 mA cm−2. • Integration of electrically conjugated polymers with non-precious metal phosphates boosts HER catalytic efficiency. • The development of CoP 2 /THQ@NF hybrid electrocatalysts through systematic methodological approaches is overviewed. • Merging organic polymers with inorganic materials elevates the catalytic prowess of non-precious metal catalysts. [ABSTRACT FROM AUTHOR]

In this study, we synthesized Co2P nanoparticles using a solid-state phosphorization method and evaluated the electrocatalytic response to glucose oxidation reaction (GORs). The influence of synthesis conditions on the particle size, morphology of Co2P species and formation of byproducts is discussed. A lower molar ratio of the phosphorus precursor leads to a decrease in the generation of byproducts. In addition, the calcination temperature and time greatly influence the purity level of the Co2P species and its particle size. Thus, we obtained three pure Co2P nanoparticles with different sizes and morphologies. Significant differences in their electrocatalytic activity against the GOR are observed depending on the size of the particles, being the smaller ones the most efficient. Based on Tafel analysis, a higher catalytic activity was observed for the carbon fibre (CF)/Co2P composite compared to Co2P, which presented a greater onset potential and low response in current density. Tafel slopes close to 120 mV/dec were obtained for both materials, indicating that the mechanism is independent of the type of Co2P-based material used. Finally, the performance of the GCE/CF/Co2P sensor was demonstrated by amperometric measurements, with a sensitivity of 409 µAmM-1cm-2, a linear range between 39.4 µM and 150 µM, and a detection limit of 0.97 µM, analytical characteristics better than those obtained for other cobalt phosphide-based sensors reported in the literature. In addition, the GCE/CF/Co2P sensor shows excellent selectivity and demonstrated to be competitive compared to other Co-based non-enzymatic glucose sensors.

The coupling of cobalt and cobalt phosphides has been demonstrated to be an efficient strategy to enhance the catalytic activity for hydrogen evolution reaction (HER). Herein, the lignin-based carbon encapsulated cobalt/cobalt phosphides heterojunctions (Co/Co 2 P@LGC) was synthesized successfully on the lignin-based carbon by carbothermal reduction integrated with post-phosphidation. The strong coupling interaction in the heterostructure promoted the establishment of a distinct synergy effect between Co and P atoms, resulting in the redistribution of electronic structure. The outstanding porous sheet structure of lignin-derived carbon facilitated the exposure of more accessible active sites and self-dopants were conducive to the formation of more carbon defects. As expected, the best catalysts, Co/Co 2 P@LGC-450 exhibited excellent HER performance in 0.5 M H 2 SO 4 , which afford a current density of 10 mA/cm2 with only 150 mV and a Tafel slope of 86 mV dec−1, as well as a robust stability for 120 h at 10 mA cm−2. This research not only presented a facile method for heterostructure electrocatalysts preparation, but also offered crucial insights into the lignin valorisation. [Display omitted] • The Co/Co 2 P@LGC was prepared via simplistic carbothermal reduction integrated with post-phosphidation method. • Effects of Co/Co 2 P heterogeneous structure on the electrocatalytic properties of Co/Co 2 P@LGC was revealed. • The relationship of heterojunction structures, phosphidation temperature and carbon (C) defects was discussed. [ABSTRACT FROM AUTHOR]

Developing non-noble-metal electrocatalysts for hydrogen evolution reactions with high activity and stability is the key issue in green hydrogen generation based on electrolytic water splitting. It has been recognized that the stacking of large CoP particles limits the intrinsic activity of as-synthesized CoP catalyst for hydrogen evolution reaction. In the present study, N-Mo x C/CoP-0.5 with excellent electrocatalytic activity for hydrogen evolution reaction was prepared using N-Mo x C as decoration. A reasonable overpotential of 106 mV (at 10 mA cm−2) and a Tafel slope of 59 mV dec−1 in 1.0 M KOH solution was achieved with N-Mo x C/CoP-0.5 electrocatalyst, which exhibits superior activity even after working for 37 h. Uniformly distributed ultrafine nanoclusters of the N-Mo x C/CoP-0.5 hybrids could provide sufficient interfaces for enhanced charge transfer. The effective capacity of the hydrogen evolution reaction could be preserved in the complex, and the enlarged electrocatalytic surface area could be expected to offer more active sites for the reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-supported amorphous CoFe-P/NF electrode was fabricated by electrodeposition. • HER and PET plastic oxidation properties were promoted by CoFe-P/NF. • H 2 and formate were coproduced by energy saving electrolysis of PET hydrolyte. • The amorphous CoFe-P and surface oxide layer lead to bifunctional catalytic features. The electrocatalytic hydrogen evolution reaction (HER) coupled with oxidative transformation of plastics into commodity chemical is a promising tactic to relieve the energy shortage and white pollution problems via sustainable and profitable manner, which necessitates highly active bifunctional catalytic electrode and meticulous construction of electrolysis system. Herein, a self-supported amorphous cobalt iron phosphide onto nickel foam (NF) substrate, labeled as CoFe-P/NF, was prepared by electrodeposition, which served as bifunctional catalytic electrode for alkali hydrogen evolution reaction (HER) and selective electrooxidation of polyethylene terephthalate (PET) plastic hydrolysate toward formate. Benefiting from the abundant catalytic sites within amorphous structure, the interelement synergy and sufficient exposure of catalyst to electrolyte, the self-supported CoFe-P/NF electrode displayed low overpotential (η 100 of 168 mV at current density of J = 100 mA cm−2), decent stability for HER and fine tolerance to PET monomers. The CoFe-P/NF electrode could also catalyze selective electrooxidation of ethylene glycol (EG) component in PET hydrolysate to formate with high productivity (0.1 mmol cm-2h−1) and faradaic efficiency (FE, 90 %) at 1.5 V. The PET hydrolysate electrolysis system based on CoFe-P/NF enabled coproduction of H 2 and value added formate at lower voltage (1.52 V at J = 20 mA cm−2) and energy consumption (84 % at J = 200 mA cm−2) relative to water electrolysis. This work showcases the coproduction of H 2 fuel and formate by electrolysis of PET hydrolysate via rational design of bifunctional catalytic electrode. We believe such type of versatile catalytic electrodes can find application scenarios in electrosynthesis of more commodity chemicals and energy devices beyond the case herein. [ABSTRACT FROM AUTHOR]

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The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy. Ammonia borane (AB) has regarded as a competitive candidate for chemical hydrogen storage. However, developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge. Herein, cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure, and function as hydrogen evolution photocatalysts. Impressively, the Co2P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min-1, outperforming most of the noble-metal-free catalysts reported to date. This remarkable performance is attributed to its desired nanosheets structure, featuring with high specific surface area, abundant exposed active sites, and short charge diffusion paths. Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting offers a most promising pathway for "green hydrogen" generation. Even so, it remains a struggle to improve the electrocatalytic performance of non‐noble metal catalysts, especially bifunctional electrocatalysts. Herein, aiming to accelerate the hydrogen and oxygen evolution reactions, an oxygen‐bridged cobalt–chromium (Co‐O‐Cr) dual‐sites catalyst anchored on cobalt phosphide synthesized through MOF‐mediation are proposed. By utilizing the filling characteristics of 3d orbitals and modulated local electronic structure of the catalytic active site, the well‐designed catalyst requires only an external voltage of 1.53 V to deliver the current density of 20 mA cm−2 during the process of water splitting apart from the superb HER and OER activity with a low overpotential of 87 and 203 mV at a current density of 10 mA cm−2, respectively. Moreover, density functional theory (DFT) calculations are utilized to unravel mechanistic investigations, including the accelerated adsorption and dissociation process of H2O on the Co‐O‐Cr moiety surface, the down‐shifted d‐band center, a lowered energy barrier for the OER and so on. This work offers a design direction for optimizing catalytic activity toward energy conversion. [ABSTRACT FROM AUTHOR]

The commonly used "catalyst on carbon" architecture as a sulfur host is difficult to jointly achieve high gravimetric and volumetric energy densities for lithium–sulfur (Li–S) batteries due to the contradiction between low tap density/poor catalytic activity of carbon and the easy agglomeration of metal‐based compounds without carbon. Here, a non‐carbon‐dominated catalytic architecture using macroporous nickel/cobalt phosphide (NiCoP) is reported as the sulfur host for Li–S batteries. The macroporous framework, which accommodates a large amount of sulfur, can accelerate the electrochemical reaction kinetics by accelerated e− transport, Li+ diffusion, and superior adsorption and catalytic activity of inherent Ni2P/CoP heterostructures. The high tap density (0.45 g cm−3) and mechanically hard features contribute to the excellent structural and physicochemical stability of the NiCoP@S electrode after the pressing and rolling process. These features enable the Li–S coin cell to exhibit excellent electrochemical performance under conditions of high sulfur loading (10.2 mg cm−2) and lean electrolyte (electrolyte/sulfur of 2 µL mg−1). Inspiringly, the assembled pouch cell can simultaneously deliver a gravimetric energy density of 345.2 Wh kg−1 and an impressive volumetric energy density of 952.7 Wh L−1 based on the entire device configuration. [ABSTRACT FROM AUTHOR]

Transition metal phosphates have proved to be promising electrocatalysts for hydrogen evolution reactions (HER) of water splitting, however, further increasing their active sites and catalytic activity remains a major challenge. Herein, accordion-like Co-MOF with layered structure was synthesized. After subsequent carbonization and phosphidization, lamellar heterostructured Co/CoP nanocrystals encapsulated in a P, N co-doped C matrix (Co/CoP@PNC) was obtained. Heterojunction provides abundant active sites and improves electron transfer rate. Additionally, the effect of phosphating degree on the electrocatalytic activity was studied. In the alkaline electrolyte, the current density of the optimized Co/CoP@PNC-10 for HER reached 10 mA cm−2 at overpotential of 137 mV in 1.0 M KOH, which was superior to most of transition metal-based electrocatalysts. This work provides new guidance for the design and development of transition metal-based electrocatalysts. Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization, the optimized Co/CoP@PNC exhibited excellent catalytic activity for alkaline HER. [Display omitted] • With accordion-like Co-MOF as the precursor, Co/CoP heterojunction embedded in P, N co-doped C matrix (Co/CoP@PNC) was prepared through further carbonization and phosphidization. • The phase and catalytic activity of the sample are related to the phosphating degree. • The optimized Co/CoP@PNC-10 exhibited the best performance among the series, with an overpotential of 137 mV at a current density of 10 mA cm−2 for alkaline HER. • P, N co-doped C substrate and Co/CoP heterojunction promote the overall HER performance through synergistic effect. [ABSTRACT FROM AUTHOR]