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The employment of hybrid perovskite MAPbX3 (MA = CH3NH3+, X = Br or I) as photocatalysts in a photocatalytic hydrogen evolution reaction represents a promising approach to store solar energy. However, the toxicity of Pb makes these materials difficult to pass environmental evaluation while the intrinsic moisture sensitivity puts forward high anhydrous requirements in photocatalysts synthesis, storage, and application, which further reduces their service life. Herein, we demonstrate a hydrogen-bond-free strategy to synthesize moisture-stable hypotoxic hybrid perovskite for photocatalytic application by replacing traditional protonated countercations with alkylated countercations in a Pb-free hybrid system, which prevents water eroding hybrid perovskites via strong hydrogen bonds. A zero-dimensional Bi-based perovskite (3-ethylbenzo[d]thiazol-3-ium)4Bi2I10 (EtbtBi2I10) was synthesized, which contains dimeric (Bi2I10)4- formed by edge-sharing (BiI6) octahedra being different from the binuclear cluster in widely studied MA3Bi2I9. Theoretical calculations indicate that the electron communication between inorganic and organic moieties is responsible for its broadband absorption with a narrow band gap of 2.04 eV. EtbtBi2I10 exhibits excellent stability in distilled water, moisture air, acid solution, and UV-light irradiation. It shows effective photocatalytic performance in HI splitting to generate hydrogen with the performance comparable with MAPbI3. Introducing electron and hole-transporting channels drastically enhances the photocatalytic reaction.

Developing of high-performance and low-cost electrocatalysts is of great significance to reduce the overpotential and accelerated the reaction rate of oxygen evolution in water splitting and related energy conversion applications. Herein, Fe, O-dual doped Ni2P (Fe, O Ni2P) nanoarray is successfully synthesized on carbon cloth demonstrating enhanced electrocatalytic activity and stability for oxygen evolution reaction (OER) under alkaline media. The as-synthesized Fe, O Ni2P nanoarray exhibits obviously improved OER performance with a low overpotential of 210 mV at 10 mA cm−2 current density and a Tafel slope of 48 mV dec−1, as well as long-term durability. The strong coupling interaction induced changes in electronic structure lead to relatively higher oxidation state and stronger oxidation ability of the Fe, O Ni2P nanoarray, together with the high electrochemical surface area and good conductivity contribute to the superior OER performance. This work highlights the anion-cation dual doping strategy may be an effective method for fabrication of catalysts relating to energy conversion applications.

Hierarchical composites represent a class of efficient electrocatalysts for renewable energy storage and conversion technologies owing to the porous structure and additional exposure of metal sites. Herein, a Ni-based metal organic frameworks (MOFs) (marked as Ni-BDC, BDC stands for 1,4-benzenedicarboxylic acid) nanosheet is successfully fabricated on hydroxyl iron oxide (FeOOH) array with carbon fiber cloth (CFC) as substrate. Benefit from the coordination tuning synergistic effect of the distinct chemical composition and the hierarchical structure for fast mass transportation, the as-obtained FeOOH@Ni-BDC illustrates excellent catalytic ability for electrochemical water oxidation with low overpotential of 270 mV to reach 10 mA/cm2 current and good durability in alkaline electrolyte. The novelty of this work lies in the modulation of electronic structure of the FeOOH with Ni-BDC through coordination effect to enhance the activity of the hierarchical composite electrocatalyst. This work is expected to guide the preparation of efficient electrocatalyst for new type alternative energy sources exploitation in near future.

We develop a method to prepare hollow FeP/Fe3O4 hybrid nanoparticles supported on carbon nanotubes (CNTs), which could be used as highly active and efficient electrocatalysts. The Fe@Fe3O4/CNT hybrids were first synthesized by annealing the CNTs adsorbed with Fe(NO3)3, followed by controlled phosphorization treatment. They exhibit an outstanding catalytic activity for oxygen evolution reaction (OER) with a low overpotential of 229 mV at a current density of 10 mA cm-2, a high turnover frequency value of 0.35 s-1 at an overpotential of 300 mV, and an ultralow Tafel slope of 27.6 mV dec-1, which is much better than that of FeP/Fe3O4, FeP/CNTs, Fe3O4/CNTs, and the commercial RuO2 electrocatalyst. More importantly, the Tafel slope is much lower than most non-noble metal-based OER electrocatalysts reported in the previous literature studies as far as we know. The excellent OER performance benefits from the electron transfer from Fe3O4 to FeP confirmed by X-ray photoelectron spectroscopy, together with good conductivity of CNTs. This hybrid structure supported on conductive CNTs may offer an efficient method to design earth-abundant and low-cost electrocatalysts for OER in practical applications.

Global environmental and energy crises have attracted wide attention and led to ongoing efforts to search for sustainable energy storage and conversion systems that can meet the energy needs of modern society. Electrocatalytic water splitting driven by renewable-energy-resource-derived electricity has been identified as a potential and practical strategy for future energy generation. Exploring nonprecious-metal-based electrocatalysts with high activity and tolerance is the prerequisite for the widespread application of this energy storage model. Heteroatom-regulated electrocatalysts with controllable components as well as electronic structure have unlimited potential toward the pursuit of high-efficiency electrocatalysts and they have been recognized as the perfect platform for establishing clear structure–property relationships. Therefore, in this review, the compositional engineering of recently reported transition-metal-compound-based water-splitting catalysts with multiple anion, cation, and zero-valent-element regulations were summarized. Particular emphasis is placed on the unique role of different doping configurations for each doping type in enhancing the electrocatalytic activities and stability of heteroatom-regulated electrocatalysts by exposing the active sites, regulating the electronic structure, and promoting the electrical conductivity. Finally, some personal perspectives on the design and development of heteroatom-doped electrocatalysts are shared to indicate the possible prospective development of transition-metal-compound-based electrocatalysts.

The environmental toxicity of Pb in inorganic–organic hybrid perovskite presents a major hurdle to commercialization, which has triggered intense research on exploring Pb-free alternatives. Soft in...

o-Nitrophenol (o-NP) and tetracycline hydrochloride (TCH) residues in various aquatic environments are two environmental contaminants, which are seriously dangerous to both social safety and the en...

Organic pollutions in wastewater are very harmful to environment and human health; their effective removal is important but still challenging. Copper iodine (CuI) is a promising semiconductor photocdatalyst, but still faces obvious drawbacks, e.g., only absorbing the UV light and serious electron-hole recombination. Herein, we report an effective hybrid copper(I) iodine-based photocatalyst [Cu4I4(EBT)5] (UJN Cu, EBT = 3-ethyl-1,3-benzothiazole-2-thione), which represents the first tetranuclear copper(I) iodine cluster been used for visible-light driven photocatalytic application. Importantly, the photocatalytic rate constant of UJN-Cu toward degrading organic dye pollution is three times larger than that for nitrogen-doped TiO2, and can retain similar activity after at least four runs. The holes are the dominated active species of photocatalyst UJN-Cu in such photocatalytic system. This work not only provides one promising copper(I) iodine-based semiconductor photocatalyst, but also unveils the feasibilities of tetranuclear copper(I) iodine cluster for wastewater purification.

Bismuth oxychloride ultrathin nanoplates (BiOCl-UTNs) are highly active, but their preparation are limited to closed-vessel hydrothermal and solvothermal techniques at high temperatures (110-180 °C). Here we report a straightforward poly(sodium 4-styrenesulfonate) (PSS)-mediated route for the large-scale synthesis of BiOCl-UTNs at room-temperature. In an open vessel, 6.15 g of BiOCl-UTNs with 3-5 nm thickness, and planar dimensions of 30-50 nm were produced. The strong electrostatic interaction between PSS and [Bi2 O2 ]2+ layers inhibited the growth rate of BiOCl nanoplates along direction, and Na+ ions governed the electrolyte sedimentation to produce BiOCl-UTNs. The resulting BiOCl-UTNs exhibited high photocatalytic activity for the degradation of antibiotics and organic dyes because of their large specific surface area, increased light absorption ability, and fast separation and transfer efficiency of the photoexcited charge carriers.

Exploring of efficient electrocatalysts based on nonprecious metals is of great importance for the development of hydrogen energy and related energy conversion technologies. Metallic Ni3Fe nanoarray is firstly fabricated on carbon cloth as efficient oxygen evolution electrocatalyst. Co, N-dual doped carbon shell derived from metal organic framework is coated on the Ni3Fe nanoarray to enhance electrocatalytic activity and stability. The as-prepared composite catalyst only needs a low overpotential of 170 mV to drive 10 mA cm−2 current density in alkaline solution, and an overpotential of 370 mV in carbonate buffer solution. Moreover, the catalyst exhibit excellent durability in both alkaline and carbonate electrolyte. Good conductivity, rich active sites, fast electron transport process and synergistic effect between Ni3Fe and the doped carbon together contributes to the efficient catalytic performance. This synthesis approach provides a new way to develop efficient nonprecious metal based electrocatalysts for water oxidation and other energy-related applications.

Facile fabrication of high-performance catalyst based on low-cost metals for sustainable hydrogen evolution is still a matter of cardinal significance. However, synthetic approaches for electrocatalyst are usually complicated and the yields are often low. Herein, we report a one-step simple method for the large-scale synthesis of Co/Ni-MoO2 composite as efficient and stable hydrogen evolution reaction (HER) electrocatalyst to drive 10 mA cm−2 current density with a low overpotential of 103 mV in basic media. Co-MoO2 and Ni-MoO2 were also prepared using this method with overpotential of 137 and 130 mV, respectively, to gain the same current density. These results indicate that this facile synthesis approach is of great practical importance as it can be easily used for large-scale preparation of electrocatalysts in industry.

A facile and scalable one-step thermal treatment method is developed to produce Co/CoOx encapsulated in N-, O-, and S-tridoped three-dimensional porous carbon material to catalytic hydrogen evoluti...

Active site number, water dissociation, and hydrogen adsorption free energy are the three main parameters for regulating the activity of electrocatalysts for hydrogen evolution reaction (HER) in alkaline media. However, at present, simultaneous modulations of these three parameters for alkaline HER still remain challenging. In this work, we take CoP as the model material and demonstrate that a metal and nonmetal dual-doping strategy can achieve simultaneous modulation of these three parameters by inducing lattice irregularity and optimizing the electronic configuration in CoP nanomaterials. Benefiting from the oxygen and copper dual-doping collective effect, the optimized O,Cu–CoP nanowire array electrode shows nearly 10-fold enhancement in catalytic activity for alkaline HER compared to a pure CoP nanowire electrode. Our work may provide a new concept to boost performance of nonprecious metal electrocatalysts for alkaline HER.

We report a simple method for preparation of self-supported nanoporous Cu-doped CoP nanorod arrays on carbon cloth (Cu-CoP NRAs/CC) by a hydrothermal and low-temperature phosphidation process, whic...

We develop a facile laser-irradiation induced alloying and subsequent chemical etching method to prepare spongy AuAgPt alloy nanospheres (spongy AuAgPt NSs) with high-index facets, rich grain boundaries and subtle lattice distortion as highly active electrooxidation catalysts. The key to preparing such spongy AuAgPt NSs for their excellent electrocatalytic activity is the alloying process induced by laser irradiation, forming rich grain boundaries and subtle lattice distortion due to the quick fusion and quenching process, which is completely different from traditional thermal annealing alloying. After chemical dealloying, the nanopores were formed and a large amount of high-index facets were successfully introduced into the spongy AuAgPt NSs. The spongy AuAgPt NSs exhibited superior methanol oxidation reaction (MOR) activity (1.62 A mgPt−1), which was 5.1 times higher than that of Pt black (0.32 A mgPt−1), and they also showed outstanding stability for the MOR after long-term cycles. The enhanced catalytic activity could be attributed to the abundant high-index facets, grain boundaries and subtle lattice distortion of spongy AuAgPt NSs formed in this laser-irradiation induced alloying and subsequent chemical etching process. The present work provides a new efficient strategy for the rational design of 3D spongy electrocatalysts with both high activity and improved durability for promising applications in electrocatalysis, biosensing, energy conversion, etc.

Currently, for overall water splitting, the highest activity for hydrogen evolution reaction (HER) oxygen evolution reaction (OER) are recorded by platinum (Pt) and ruthenium oxide (RuO2) catalysts, respectively. However, the shortage and sumptuosity of these noble metals limit their commercial applications. Herein, we prepared Ni0.33Co0.67MoS4 nanosheets on carbon fiber cloth (Ni0.33Co0.67MoS4/CFC) as bifunctional electrolytic water catalysts for both HER and OER. In the HER process, Ni0.33Co0.67MoS4/CFC exhibited an overpotential of only 48.0 mV at a current density of 10 mA cm−2, and the Tafel slope was 73.5 mV dec−1. Moreover, in the OER process, Ni0.33Co0.67MoS4/CFC displayed a low overpotential of 283 mV at current densities of 10 mA cm−2, and the Tafel slope was 68.8 mV dec−1. More importantly, Ni0.33Co0.67MoS4/CFC could act as a bifunctional electrocatalyst to split water under a cell voltage of 1.55 V at a current density of 10 mA cm−2. In addition, negligible decay occurred after 20 h of continuous electrolysis testing. Such noble-metal-free electrocatalysts may provide a strategy for the design of high efficiency overall water splitting catalysts, which are expected to be applied to the actual electrolysis water industry.

Development of efficient catalyst with low-cost, earth-abundant metals for sustainable hydrogen generation is still an intriguing challenge. Doping of cation or anion is regarded as an effective approach for ingenious modulation of chemical composition related to the electrocatalysts for improving their activity. Herein, a ternary Ni(S0.49Se0.51)2 porous flakes array on carbon fiber cloth (CFC) via simultaneous sulfuration and selenylation of Ni(OH)2 flakes. Owing to the synergistic effect between Ni, S and Se atoms, high surface area, abundant active site and good conductivity of the Ni(S0.49Se0.51)2/CFC, the as-synthesized catalyst requires lower overpotential (113 mV) than pure NiS2/CFC and NiSe2/CFC to drive 10 mA cm−2 for hydrogen evolution reaction (HER) in 1.0 M KOH with good sustainability.

We developed an interesting route for preparing a poly (acrylamide-co-acrylic acid) (P(AAm-co-AA)) hydrogel microsphere with a coating of Au nanospheres (hydrogel microsphere @ Au nanospheres) through self-assembly based on electrostatic interaction. The fabricated composites could be used as highly sensitive enhanced Raman scattering substrates. The nanogaps between adjacent Au nanospheres were dynamically tuned by volume changes in the hydrogel microspheres in the semiwet state under different pH conditions. At pH 6, the hydrogel microsphere @ Au nanospheres demonstrated highly sensitive SERS with an enhancement factor of 109. The product could detect very low concentrations of analytes up to 10-12M 4-aminothiophenol (4-ATP) molecules. This paper proposes a new method for detecting trace amounts of environmental organic pollutants by dynamically tuning the SERS enhancement in the semiwet testing state.

High-quality Au@ZnO core–shell nanoparticle (NP) array films were easily and efficiently fabricated through an air/water interfacial self-assembly. These materials have remarkable visible light absorption capacity and fascinating performance in photoelectrochemical (PEC) water splitting with a photocurrent density of ∼3.08 mA/cm2 at 0.4 V, which is superior to most ZnO-based photoelectrodes in studies. Additionally, the interesting PEC performance could be effectively adjusted by altering the thickness of the ZnO shell and/or the layer number of the array films. Results indicated that the bilayer film based on Au@ZnO NPs with 25 nm shell thickness displayed optimal behavior. The remarkable PEC capability could be ascribed to the enhanced light-harvesting ability of the Au@ZnO structured NPs by the SPR effect and the optimum film thickness. This work demonstrates a desirable paradigm for preparing photoelectrodes based on the synergistic effect of plasmatic NPs as the core and a visible optical absorbent a...

Great efforts have been made to understand and upgrade the kinetically sluggish oxygen evolution reaction (OER). In this study, a series of V-doped LaCoO3 (V-LCO) OER electrocatalysts with optimized d-band centers are fabricated. When utilized as an electrode for the OER, as-formed LaCo0.8 V0.2 O3 (V-LCO-II) requires an overpotential of only 306 mV to drive a geometrical catalytic current density of 10 mA cm-2 . Furthermore, at a given overpotential of 350 mV, the OER current density of V-LCO-II is about 22 times that of pure LaCoO3 (LCO) nanoparticles. Tailoring of the d-band center by V doping facilitates the adsorption of OER intermediates and promotes the formation of amorphous active species on the surface of LCO through the exchange interaction between high-spin V4+ and low-spin Co2+ . This work may create new opportunities for developing other highly active OER catalysts through d-band center engineering.

We report the successful synthesis of Mo doped Ni2P nanowires (NWs) on a Ni foam (NF) substrate by a two-step strategy, which could be used as an efficient and stable hydrogen evolution reaction (HER) electrocatalyst over the whole pH range (0–14). Electrochemical investigations demonstrated that Mo doping made the catalytic activity of Ni2P significantly enhanced. To achieve a current density of 10 mA cm−2, Mo–Ni2P NWs/NF required an overpotential of 67 mV in acidic solution, 78 mV in alkaline solution and 84 mV in neutral solution. It also showed superior stability with negligible activity decay after its use in the HER under different pH conditions for 24 h. Such excellent HER activity might originate from the synergistic effect between molybdenum (Mo) and nickel (Ni) atoms. The present work provides a valuable route for the design and synthesis of inexpensive and efficient all-pH HER electrocatalysts.

Hierarchical micro/nanostructured C doped Co/Co3O4 hollow spheres were prepared by two-step treatment (annealing at 600 °C in an Ar atmosphere and then at 250 °C in air) of PS@Co(OH)2 core–shell structures templated from PS microspheres without any modification. In 1 M KOH, such hollow nanospheres showed an overpotential of 352 mV at a benchmark oxygen evolution reaction (OER) current density of 10 mA cm−2, which was lower than that of RuO2 (364 mV), Co3O4 hollow nanospheres (410 mV) and C-Co/Co3O4 nanoparticles (462 mV). Importantly, the C-Co/Co3O4 hollow spheres exhibited a small onset potential (1.49 V) due to their more active sites, higher electrical conductivity, larger specific surface area, and excellent electron and ion diffusion permeability. This work provides a strategy to design and fabricate earth-abundant, low-cost electrocatalysts for water splitting in practical applications.

We develop an interesting route to prepare new sponge-like Au–Ag alloy nanocubes (NCs) with controlled porosity and atomic percentage through an interparticle alloying and dealloying process. Au@Ag NCs were first synthesized using Au nanooctahedra as initial seeds. Then, the Au@Ag NCs were covered with SiO2 and thermally annealed, forming solid Au–Ag alloy NCs with a SiO2 layer. After removing the majority of the SiO2 layer and leaching less-stable Ag from solid Au–Ag alloy NCs, uniform sponge-like porous Au–Ag alloy NCs were obtained. In this process, SiO2 not only prevents fusion between adjacent Au@Ag NPs under thermal annealing, but also directs the final shape of sponge-like Au–Ag alloy NPs with a cubic shape as a template. Thanks to the high-density “hotspots” in nanopores, sharp corners and edges, and a synergistic effect between Au and Ag species, such sponge-like Au–Ag alloy NCs showed excellent SERS performance with an enhancement factor of ∼108, which can effectively detect 4-aminothiophenol (4-ATP) at a concentration as low as 1 × 10−10 M. This strategy is universal and it can be extended to prepare sponge-like Au–Ag alloy NPs with different accurate shapes. Such sponge-like nanoporous alloy NPs have many potential applications such as in plasmonics, SERS, drug delivery, photothermal therapy, and catalysis systems.

The large-scale implementation of hydrogen by electrochemical water splitting demands highly active, durable and inexpensive platinum-free catalysts. Nevertheless, developing efficient non-noble metal based hydrogen evolution reaction (HER) electrocatalysts that can work in all pH solutions still remains as a huge uphill. Herein, we report dual zerovalent nonmetal (N and B) doped Ni2P nanoparticles hybridized with N, B-graphene (N, B-Ni2P/G) could function as electrocatalyst for hydrogen evolution in all pHs with high activity and stability. In-situ phosphidation of a 2D/2D heterojunction of Ni-Bi nanosheets/graphene (Ni-Bi NS/G) under ammonia atmosphere results in a strongly couple N, B-Ni2P/G hybrid electrocatalyst with (i) the enhanced intrinsic catalytic activity from dual zerovalent doped Ni2P structure, (ii) 0D architectures with a high surface area exposure yield, and (iii) the enhanced charge transport ability by N, B-graphene support. As a result, the designed N, B-Ni2P/G exhibits superior electrocatalytic HER performance and remarkable stability at all pH ranges. Our protocol may open up new ways to design progressive electrocatalysts for energy-related applications.

Noble metal particles (Au and Ag) with porous structure are promising surface-enhanced Raman scattering (SERS) substrates, but their preparation processes are generally complex. Here, we report a remarkably facile, rapid and inexpensive method to synthesize two kinds of porous Ag submicrocubes, cage- and sponge-like submicrocubes with highly clean and accessible surfaces. These particles were synthesized in a completely green solvent (water) by using Ag3PO4 submicrocubes as templates at room temperature. Merely by optimizing the concentration of a reducing agent (NaBH4), three-dimensional cage- and sponge-like Ag submicrocubes were fabricated. As a result, as SERS substrates, the cage- and sponge-like Ag submicrocubes can achieve near-infrared (NIR)-SERS activity because they have broad absorption throughout the visible and NIR regions. Moreover, compared with the sponge-like Ag submicrocubes, cage-like submicrocubes with a highly rough surface had higher SERS enhancement due to the presence of narrow and deep nanoslits on their shells. Due to the high-density of ‘‘hot spots’’ produced by the narrow and deep nanoslits on the shell, cage-like Ag submicrocubes have a low SERS detection limit, 1.479 × 10−11 M for 4-aminothiophenol and 1.50 × 10−9 M for thiram. Thus, a new SERS substrate based on highly rough cage-like submicrocubes was obtained by an easy and green method.

Designing highly active electrocatalysts based on earth-abundant metals is attracting great interest for the development of renewable energies. In this work, NiTe2/Ni(OH)2 hybrid nanosheet is successfully fabricated on carbon fiber cloth by a successive hydrothermal reaction for the first time, showing excellent catalytic performance for both electrochemical water oxidation and urea oxidation reaction. Benefiting from the unique electron property of NiTe2 and strong synergistic interaction between NiTe2 and Ni(OH)2, the as-obtained hybrid catalyst only need an overpotential of 267 mV to achieve a current density of 10 mA cm−2 in 1.0 M KOH, and achieve 73 mA/cm2 at 1.523 V in 1.0 M KOH with 0.33 M urea. The innovation of this work is the incorporation of NiTe2 and Ni(OH)2 to boost its catalytic ability. This novel method is expected to provide new chance for developing efficient catalysts for energy conversion application.

Indoor formaldehyde (HCHO) removal is very important to reduce public health risk. Herein, we report a facile method for preparing N-doped nanoporous carbon through direct carbonization of metal-organic frameworks (ZIF-8) to remove harmful formaldehyde. The prepared N-doped nanoporous carbon exhibited uniform morphology and large specific surface area. Moreover, the type of N-functional groups on the N-doped nanoporous carbon had a dominant effect on its HCHO adsorption activity. As a result, HCHO adsorption capacity of the optimized N-doped nanoporous carbon was approximately five times higher than that of the commercially activated carbon. The detailed HCHO adsorption process, including physical adsorption and chemical adsorption, was also confirmed through in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In addition, it should be noted that the N-doped nanoporous carbon exhibited high stability for HCHO adsorption, even after six adsorption cycles, indicating its good recyclability for long-term application. This study is expected to pave a way for expanding the environmental applications of the N-doped nanoporous carbon.

Periodic porous alloyed Au–Ag nanosphere (NS) arrays with different periodic lengths and tunable composition ratios were prepared on Si substrates on a large scale (∼cm2) using stepwise metal deposition-annealing and subsequent chemical corrosion from a monolayer of colloidal polystyrene (PS) microspheres as the initial template. The porous alloyed Au–Ag NSs possessed a high porosity and bicontinuous morphology composed of hierarchically interconnected ligaments, which were obtained from an optimized dealloying process in nitric acid. Interestingly, when the dealloying time was prolonged, the average size of the porous alloyed NSs slightly decreased, and the width of the ligaments gradually increased. The periodic length of the array could be facilely changed by controlling the initial particle size of the PS template. Moreover, the porous alloyed Au–Ag NS arrays were explored as a platform for the surface-enhanced Raman scattering (SERS) detection of 4-aminothiophenol (4-ATP) and exhibited excellent repr...

Periodic gold nanosphere arrays were prepared on a planar silicon substrate, which could be directly developed as an electrode to sensitively and selectively detect H2O2 without an enzyme via an electrochemical method. The arrays of Au nanospheres were fabricated on a large scale (∼cm2) on the Si substrate using polystyrene (PS) colloidal monolayers as the template, after Au deposition and subsequent annealing. The developed biosensor based on the Au nanosphere arrays on the Si substrate demonstrated excellent catalytic activity towards H2O2 over a wide linear range of 0.2 μM–5 mM with a very low detection limit of 0.1 μM. Importantly, the electrochemical biosensor possessed good stability and high reproducibility. The catalytic activity can be enhanced by reducing the gold nanoparticle size and periodic length in the array. The biosensors based on periodic Au nanosphere arrays used to determine the concentration of H2O2 have the advantages of non-enzymatic detection and non-Pt electrode strategy when compared to the conventional method, which may open up new horizons in the production of outstanding biosensors and can be used as a platform for the preparation of various electrochemical biosensors.

We report the successful synthesis of Mn doped CoN nanowires on a carbon fiber cloth substrate (CFC) by a two-step strategy, which can be used as an efficient and stable OER electrocatalyst under both alkaline and neutral conditions. Benefiting from enhanced electronic interaction, high active area and electrical conductivity, the Mn doped CoN nanowires/CFC exhibits enhanced kinetics and improved cycling stability for the OER under both alkaline and neutral conditions. To achieve a current density of 10 mA cm−2, the Mn doped CoN nanowires/CFC requires an overpotential of 265 mV in alkaline solution and 285 mV in neutral solution.

Uniform Au nanoparticle (NP)/poly (acrylamide-co-acrylic acid) [P(AAm-co-AA)] hydrogel microbeads were successfully prepared using droplet microfluidics technology. The microbeads exhibited a good stimuli-responsive behavior to pH value. Particularly in the pH value ranging from pH 2-pH 9, the composite microbead sizes gradually increased along with the increase of pH value. The homogeneous Au NPs, which were encapsulated in the P(AAm-co-AA) hydrogel microbeads, could transform the volume changes of hydrogel into optical signals by a tested single microbead with a microspectrometre system. The glucose was translated into gluconic acid by glucose oxidase. Thus, the Au NP/P(AAm-co-AA) hydrogel microbeads were used for detecting glucose based on pH effects on the composite microbeads. For this, the single Au NP/P(AAm-co-AA) hydrogel microbead could act as a good pH- or glucose-visualizing sensor.

Exploring highly efficient and low-cost electrocatalysts for electrochemical water splitting is of importance for the conversion of intermediate energy. Herein, the synthesis of dual-cation (Fe, Co)-incorporated NiSe2 nanosheets (Fe, Co-NiSe2 ) and systematical investigation of their electrocatalytic performance for water splitting as a function of the composition are reported. The dual-cation incorporation can distort the lattice and induce stronger electronic interaction, leading to increased active site exposure and optimized adsorption energy of reaction intermediates compared to single-cation-doped or pure NiSe2 . As a result, the obtained Fe0.09 Co0.13 -NiSe2 porous nanosheet electrode shows an optimized catalytic activity with a low overpotential of 251 mV for oxygen evolution reaction and 92 mV for hydrogen evolution reaction (both at 10 mA cm-2 in 1 m KOH). When used as bifunctional electrodes for overall water splitting, the current density of 10 mA cm-2 is achieved at a low cell voltage of 1.52 V. This work highlights the importance of dual-cation doping in enhancing the electrocatalyst performance of transition metal dichalcogenides.

We report the preparation of MnMoO4 nanosheet array on nickel foam (MnMoO4 NSA/NF) as an excellent 3D hydrogen evolution reaction (HER) electrocatalyst with good catalytic performance applied under basic, acidic and neutral conditions. In 0.5 M H2SO4, this MnMoO4 NSA/NF electrode needs an overpotential of 89 mV to drive current densities of 10 mA cm-2, to achieve the same current density, it demands overpotentials of 105 mV in 1.0 M KOH, 161 mV in 1.0 M PBS (pH = 7), respectively. After continuous CV scanning for 1000 cycles under different pH conditions, it also demonstrates an excellent stability with ignorable activity decrease. Such preeminent HER performance may be derived from the synergistic effect between manganese (Mn) and molybdenum (Mo) atoms, exposure of more active sites on the nanosheets and effective electron transport along the nanosheets. This MnMoO4 NSA/NF electrocatalyst provides us a highly efficient material for water splitting devices for industrial hydrogen production.