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Hydrogen evolution reaction (HER) in neutral media is of great practical importance for sustainable hydrogen production, but generally suffers from low activities, the cause of which has been a puzzle yet to be solved. Herein, by investigating the synergy between Ru single atoms (RuNC) and RuSex cluster compounds (RuSex) for HER using ab initio molecular dynamics, operando X-ray absorption spectroscopy, and operando surface-enhanced infrared absorption spectroscopy, we establish that the interfacial water governs neutral HER. The rigid interfacial water layer in neutral media would inhibit the transport of H2O*/OH* at the electrode/electrolyte interface of RuNC, but the RuSex can promote H2O*/OH* transport to increase the number of available H2O* on RuNC by disordering the interfacial water network. With the synergy of RuSex and RuNC, the resulting neutral HER performance in terms of mass-specific activity is 6.7 times higher than that of 20 wt.% Pt/C at overpotential of 100 mV. Understanding the slow kinetics of hydrogen evolution reaction in neutral media is of fundamental importance for the rational design of high-performance electrocatalysts for hydrogen energy. Here, by studying Ru single atom and RuSex cluster, the authors report how the rate of hydrogen evolution reaction activity in neutral media is governed by interfacial water. [ABSTRACT FROM AUTHOR]

The development of highly active and stable bifunctional noble‐metal‐based electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a crucial goal for clean and renewable energy, which still remains challenging. Herein, we report an efficient and stable catalyst comprising a Co single atom incorporated in an RuO2 sphere for HER and OER, in which the Co single atom in the RuO2 sphere was confirmed by XAS, AC‐STEM, and DFT. This tailoring strategy uses a Co single atom to modify the electronic structures of the surrounding Ru atoms and thereby remarkably elevates the electrocatalytic activities. The catalyst requires ultralow overpotentials, 45 mV for HER and 200 mV for OER, to deliver a current density of 10 mA cm−2. The theoretical calculations reveal that the energy barriers for HER and OER are lowered after incorporation of a cobalt single atom. [ABSTRACT FROM AUTHOR]

As an important regulatory method, the phase engineering strategy is widely used to develop functional materials with desired properties. Herein, we combine a solvothermal method with post‐annealing treatment to controllably synthesize multifunctional MoSe2 flower‐like nanostructures (FNSs) in different crystal phases. Based on the different phases of MoSe2 FNSs, we systematically investigate their performance in lithium‐ion storage, the hydrogen evolution reaction (HER), and the hydrogenation of nitrophenol. The results show that 1T‐MoSe2 FNSs possess superior performance in lithium‐ion batteries, HER, and hydrogenation of PNP compared with 2H‐MoSe2 FNSs. Moreover, density functional theory calculations reveal that 1T‐MoSe2 FNSs exhibits a higher chemisorption energy than that of 2H‐MoSe2 FNSs, which is beneficial for the improvement of the lithium‐ion storage capacity. This work provides an effective way to develop functional materials based on phase engineering. [ABSTRACT FROM AUTHOR]

For electrocatalysts for the hydrogen evolution reaction (HER), encapsulating transition metal phosphides (TMPs) into nitrogen‐doped carbon materials has been known as an effective strategy to elevate the activity and stability. Yet still, it remains unclear how the TMPs work synergistically with the N‐doped support, and which N configuration (pyridinic N, pyrrolic N, or graphitic N) contributes predominantly to the synergy. Here we present a HER electrocatalyst (denoted as MoP@NCHSs) comprising MoP nanoparticles encapsulated in N‐doped carbon hollow spheres, which displays excellent activity and stability for HER in alkaline media. Results of experimental investigations and theoretical calculations indicate that the synergy between MoP and the pyridinic N can most effectively promote the HER in alkaline media. [ABSTRACT FROM AUTHOR]

The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo-SAs) supported on N-doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo-SAs anchored with one nitrogen atom and two carbon atoms (Mo1N1C2). Importantly, the Mo1N1C2 catalyst displayed much more excellent activity compared with Mo2C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo1N1C2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo-based HER catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bifunctional Mo1@CNNTs photocatalyst was prepared through a facile strategy. • Mo1@CNNTs achieved 97.3% TC degradation and 4861µmolh−1 g−1 H 2 evolution rate. • Unveiled critical role of atomic Mo sites in activating O 2 into reactive species. • O 2 activation and H 2 evolution mechanisms were revealed by DFT calculations. Metal single atom catalysts (MSACs) stabilized by nitrogen in carbon nitride are intriguing photocatalysts for energy and environmental applications. However, the synergistic effect of simultaneously tailoring the carbon nitride nanostructure and fabricating single metal atoms has not been explored for photocatalysis. Herein, we report the facile synthesis of Mo atomic sites on porous carbon nitride nanotubes (Mo1@CNNTs) obtained by template free polymerization of urea and melamine monomers. AC-HAADF-STEM image confirmed the existence of isolated Mo atoms, while XAS analysis revealed the formation of unique atomic Mo-N 3 structures on CNNTs. Incorporation of Mo atomic sites into CNNTs modulated electronic and band structure and thus improved light harvesting, charge separation, and transfer. The synergy of 1D nanotube structure and distinct atomic Mo sites turned Mo1@CNNTs as a highly efficient bifunctional photocatalyst for hydrogen evolution and tetracycline degradation. On one side Mo1@CNNTs demonstrated hydrogen evolution rate of 4861 µmol.h−1.g−1, while on the other hand Mo1@CNNTs achieved 97.3% TC degradation under visible light irradiation. DFT investigations revealed that induction of unique Mo atomic sites not only tuned the electronic structure of CNNTs, but also localized photoexcited electrons around Mo atoms to activate O 2 (ads) and generate reactive species (.O 2 –/.OH) for TC degradation. We believe that our findings are promising and will open new opportunities for the design of novel photocatalyst for a sustainable future. [ABSTRACT FROM AUTHOR]

Defects in nanocarbon materials can trigger their intriguing electrochemical properties and potential applications, but their synthesis is challenging. Herein, we report the synthesis of ultrathin nitrogen-doped carbon nanosheets with intrinsic defects through the pyrolysis of ZIF-8 with linker vacancies. The as-synthesized electrocatalyst exhibits excellent oxygen reduction reaction (ORR) activity with an onset potential and half-wave potential of 1.05 and 0.873 V vs. RHE, respectively, outperforming the reported metal-free ORR electrocatalysts. It also shows a commercial Pt/C-comparable performance in zinc–air battery with a power density of 154.4 mW cm−2. Characterization and DFT calculation results suggest the adjacent sp3-carbon in carbon pentagon can significantly strengthen the adsorption and activation of oxygen molecules on sp2-carbon, hence the potential determining step is altered and ORR overpotential is lowered. This work highlights a promising green synthesis strategy of MOF-derived metal-free nanocarbon materials for wide application in advanced energy technologies. [Display omitted] • Hydrothemal synthesis of ZIF-8 with linker vacancies by addition of boric acid. • Rich edge sites, carbon pentagon and sp3 hybrization in derived metal-free carbon. • Superior ORR and zinc–air battery performance among reported metal-free materials. • Synergistic effect of topological defect and hybrization state. [ABSTRACT FROM AUTHOR]

Constructing well defined nanostructures is promising but still challenging for high‐efficiency catalysts for hydrogen evolution reaction (HER) and energy storage. Herein, utilizing the differences in surface energies between (111) facets of CoP and NiCoP, a novel CoP/NiCoP heterojunction is designed and synthesized with a nanotadpoles (NTs)‐like morphology via a solid‐state phase transformation strategy. By effective interface construction, the disorder in terms of electronic structure and coordination environment at the interface in CoP/NiCoP NTs is created, which leads to dramatically elevated HER performance within a wide pH range. Theoretical calculations prove that an optimized proton chemisorption and H2O dissociation are achieved by an optimized phosphide polymorph at the interface, accelerating the HER reaction. The CoP/NiCoP NTs are also proved to be excellent candidates for use in supercapacitors (SCs) with a high specific capacitance (1106.2 F g−1 at 1 A g−1) and good cycling stability (nearly 100% initial capacity retention after 1000 cycles). An asymmetric supercapacitor shows a high energy density (145 F g−1 at 1 A g−1) and good cycling stability (capacitance retention is 95% after 3200 cycles). This work provides new insights into the catalyst design for electrocatalytic and energy storage applications. [ABSTRACT FROM AUTHOR]

A novel in situ strategy to embed Co 9 S 8 nanoparticles into nitrogen and sulfur codoped hollow porous carbon (Co 9 S 8 @N-S-HPC) is achieved. The Co 9 S 8 @N-S-HPC can be used an efficient catalyst for both ORR and HER. The unique nanostructure and synergistic interactions between Co 9 S 8 and N-S-HPC play a crucial role to improve the electrocatalytic performance. • Co 9 S 8 @N-S-HPC is fabricated using a novel in situ formation approach. • Co 9 S 8 @N-S-HPC shows excellent electrocatalytic performance toward ORR and HER. • Synergistic effect of Co 9 S 8 and N-S-HPC improves the electrocatalytic performance. The oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) are critical processes for many energy conversion technologies, where efficient catalyst plays a key role in these reactions. Here we report a novel in situ strategy to embed Co 9 S 8 nanoparticles (NPs) into nitrogen and sulfur codoped hollow porous carbon (Co 9 S 8 @N-S-HPC). In this strategy, the ZIF-8 surface is firstly decorated by cobalt thiourea, and then coated with a shell of polymeric resorcinol-formaldehyde, followed by a high temperature pyrolysis treatment. The resulting Co 9 S 8 @N-S-HPC shows comparable catalytic activity for ORR compared with commercial 20 wt% Pt/C catalyst and superior long-term stability under alkaline conditions. Simultaneously, Co 9 S 8 @N-S-HPC also exhibits an excellent HER activity with low onset overpotential of 68 mV, a small Tafel slope of 78 mV per decade and a long-term durability in alkaline medium. First-principles calculations reveal that Co 9 S 8 particle can anchor in N-S-HPC via a Co-S bond and enhance the binding of Co 9 S 8 and N-S-HPC. The N-S-HPC can affect the electronic structure of supported Co 9 S 8 strongly. The combined experimental and theoretical investigation show the outstanding ORR and HER performances of Co 9 S 8 @N-S-HPC are attributed to its unique nanostructure and synergistic interactions between Co 9 S 8 NPs and N-S-HPC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe2+-induced oxygen vacancy strategy was developed to construct robust OER catalysts. • Ni/β-FeOOH-1/CC shows an ultralow overpotential of 192 mV at 10 mA·cm−2. • The high OER activity is attributed to the massive oxygen vacancies and Ni doping. • Ni/β-FeOOH-1/CC can drive overall water splitting by dry battery or GaAs solar cell. • Ni/β-FeOOH-1/CC can realize an industrial-scale current density of 300 mA·cm−2. Abundant oxygen-vacancy and heteroatomic doping have been demonstrated to be beneficial to obtain high electrocatalytic performance for the oxygen evolution reaction (OER). In present work, a simple cathodic electrodeposition (CED) method based on Fe(II)-induced oxygen deficiency-metal doping (FeIIIOD/MD) strategy was developed to prepare robust water oxidation electrocatalysts. By using Fe2+ ions as the iron precursors, a series of Ni-doped β-FeOOH (Ni/β-FeOOH- x) on the carbon cloth (Ni/β-FeOOH- x /CC, here, the × is the molar percent of Fe2+ in the total ferric salt; x = 0, 0.2, 0.5, 0.8 or 1) electrocatalysts with different oxygen vacancy content were prepared. Relevant characterizations indicated that the oxygen-vacancy ratio and electrocatalytic OER performances of Ni/β-FeOOH-1/CC electrocatalysts prepared by using Fe2+ ions as the iron precursor is significantly higher than that of Fe3+. Fascinatingly, the Ni/β-FeOOH-1/CC with massive oxygen vacancies shows an ultralow overpotential of 192 mV at the current density of 10 mA·cm−2. Furthermore, the Ni/β-FeOOH-1/CC catalyst can also be directly driven by a dry cell or solar cell. More importantly, the Ni/β-FeOOH-1/CC catalyst prepared by CED method based on this FeIIIOD/MD strategy can realize water oxidation at the industrial current density, and it shows a potential industrial application value in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ag@NiV 0.2 Co 0.2 is fabricated by a simple spontaneous redox reaction. • A highly active layer is formed due to the surface reconstruction and V leaching. • The oxygen-deficient (oxy)hydroxide layer is key to the enhanced OER activity. • In-situ Raman provide direct observation of surface reconstruction and active species. • Our findings provide valuable guidance to design novel electrocatalysts. The transition-metal (oxy)hydroxides have been considered as one of the promising electrocatalysts for oxygen evolution reaction (OER). Therefore, it is necessary to have in-depth study on the origin behind their favorable inherent OER activity and further improve their catalytic performance. Herein, nickel–cobalt-vanadium trimetallic (oxy)hydroxide nanosheets decorated with silver nanoparticles (Ag NPs) (Ag@NiV 0.2 Co 0.2) are fabricated for OER by a simple spontaneous redox reaction. The Ag@NiV 0.2 Co 0.2 can deliver an overpotential of only 255 mV at 10 mA cm−2 and a small Tafel slope of 38.3 mV dec-1 in alkaline solution. We accredit the outstanding catalytic performance to the following aspects: (1) the active (oxy)hydroxide layer on the surface of Ag@NiV 0.2 Co 0.2 generated through the surface reconstruction, (2) the optimal local coordination induced by the interaction between Ag NPs and trimetallic system, (3) the extensively exposed active sites, and (4) the significantly improved charge-transfer ability due to the incorporation of Ag NPs. Our findings may provide deep understanding on the mechanism of OER and offers a novel strategy to design electrocatalysts with superior OER activity. [ABSTRACT FROM AUTHOR]

• MoSe 2 nanosheets array was prepared on Mo foil by one-step solvothermal approach. • The as-prepared MoSe 2 @Mo can be directly used as an electrode to catalyze HER. • MoSe 2 @Mo shows good catalytic activity and stability in acidic and alkaline media. In this letter, we present a facile solvothermal approach for the synthesis of MoSe 2 nanosheets array on Mo foil (MoSe 2 @Mo). Mo foil served both as a Mo precursor and a substrate, on which uniformly distributed MoSe 2 nanosheets array was directly grown in situ. The as-prepared MoSe 2 @Mo catalyst exhibited great hydrogen evolution reaction (HER) electrocatalytic activity and stability in both acidic and alkaline media. [ABSTRACT FROM AUTHOR]