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Modulating Pt surfaces through the introduction of lattice distortion emerges as immensely effective strategy that enhances the kinetics of alkaline hydrogen evolution and oxidation processes. In this study, we fabricated lattice-distorted Pt wrinkled nanoparticles (LD-Pt WNPs) for efficient hydrogen electrocatalysis. The LD-Pt WNPs not only outperform the Pt/C benchmark in hydrogen oxidation reaction, achieving an excellent mass-specific current of 968.5 mA·mgPt−1 (9 times that of Pt/C), but also demonstrate outstanding hydrogen evolution reaction activity with a small overpotential of 58.0 mV. Comprehensive experiments and density functional theory calculations reveal that lattice defects introduce an abundance of unsaturated coordination atoms while modifying the d-band center of Pt. This dual effect optimizes the binding strength of crucial H and OH intermediates, leading to a significant reduction in the energy barrier of the reaction bottleneck, commonly known as the Volmer step. This work unveils a fresh viewpoint on projecting and developing high efficiency electrocatalysts through defect engineering. [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]

Noble metal electrocatalysts (e.g., Pt, Ru, etc.) suffer from sluggish kinetics of water dissociation for the electrochemical reduction of water to molecular hydrogen in alkaline and neutral pH environments. Herein, we found that an integration of Ru nanoparticles (NPs) on oxygen-deficient WO3-x manifested a 24.0-fold increase in hydrogen evolution reaction (HER) activity compared with commercial Ru/C electrocatalyst in neutral electrolyte. Oxygen-deficient WO3-x is shown to possess large capacity for storing protons, which could be transferred to the Ru NPs under cathodic potential. This significantly increases the hydrogen coverage on the surface of Ru NPs in HER and thus changes the rate-determining step of HER on Ru from water dissociation to hydrogen recombination. While water splitting electrolysis offers an appealing means to produce H2 fuel, catalysts show sluggish reaction rate in neutral media. Here, authors utilize hydrogen spillover from oxygen-deficient tungsten oxides to Ru nanoparticles to boost the neutral-pH H2 evolution performances. [ABSTRACT FROM AUTHOR]

• Simple strategy to prepare efficient electrocatalysts for alkaline HER. • Acceleration of HER kinetics on molybdenum carbide by introducing Ru components. • The synergistic effect between the introduced Ru components and molybdenum carbide. • Decrease of water dissociation energy barrier and weakening of adsorption of OH. Hydrogen evolution reaction (HER) under alkaline media plays a pivotal role in industrial electrocatalytic hydrogen production but even the platinum-based electrocatalysts suffer from high overpotential and low kinetics due to the high energy barrier of water dissociation. Here, by employing in-situ produced graphitic carbon nitride (g-C 3 N 4) as template to induce the formation of a lamellar structure, we reported evenly dispersed Ru-doped Mo 2 C nanoparticles on ultrathin nitrogen-doped carbon nanosheets (Ru-Mo 2 C/CN) as a highly efficient alkaline HER electrocatalyst. The optimal Ru-Mo 2 C/CN displays a remarkable activity with a low overpotential of only 34 mV to afford 10 mA cm−2 and good stability of more than 30 h, which is much better than that of commercial Pt/C and recently reported electrocatalysts in the landmark literatures. Density functional theory (DFT) calculations show that the introduced Ru dopant on Mo 2 C significantly reduce the water dissociation energy barrier of HER and inhibit the competitive adsorption between H* and OH* on the surrounding Mo sites. This work highlights a simple yet effective strategy for designing electrocatalysts with excellent performance of hydrogen evolution reaction in alkaline media. [ABSTRACT FROM AUTHOR]

Inspired by the excellent activity of platinum in hydrogen evolution reaction (HER) and the good performance of Ni-based compounds in oxygen evolution reaction (OER), a bifunctional electrocatalyst PtNi carbon nanofiber (CNF) is designed and fabricated using electrospinning followed by carbonization. Ultra-small PtNi nanoparticles of several nanometers in size are densely dispersed on every CNF, along with a few larger nanoparticles with sizes of several decades of nanometers. The as-prepared catalysts can be directly used as an electrode and act as high-efficiency materials for water splitting, including HER and OER. For HER activity, the PtNi/CNFs reach 10 mA cm current density at low overpotentials of 34 mV and exhibit a small Tafel slope of 31 mV dec in acidic electrolytes of 0.5 M HSO, which is close to that of commercial Pt/C (20 wt%) electrocatalytic catalysts. In 1 M KOH solution, the PtNi/CNFs also exhibit excellent HER activity with a low overpotential of 82 mV to achieve a current density of 10 mA cm and a small Tafel slope of 34 mV dec. Moreover, the PtNi/CNFs also show good activity for OER in alkaline electrolyte of 1 M KOH with a Tafel slope of 159 mV dec and a small overpotential of 151 mV to reach a current density of 10 mA cm. In addition, the OER performance of the PtNi/CNFs in acid media is also favorable, with a 198 mV dec Tafel slope. The decent activity of the PtNi/CNFs for water splitting originates from the synergistic effects of using Pt and Ni, large amounts of ultra-small nanoparticles densely dispersed on the CNFs, high conductivity of the support materials and interconnected three-dimensional structures of the carbon nanofiber mats. [ABSTRACT FROM AUTHOR]

Efficient bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be developed to realize an inexpensive water-splitting system for large-scale applications. Herein, a novel PdNi carbon nanofiber (PdNi/CNF) catalyst was synthesized by facile electrospinning and carbonization processes. The size and homogeneity of the Pd−Ni alloy nanoparticles (NPs) could be effectively tuned by controlling the molar feed ratio of metal precursors .The morphology and structure of the PdNi/CNFs were characterized, and the working electrodes fabricated from the prepared catalyst mats were directly employed in the HER and OER. The PdNi/CNFs-1:2 catalyst exhibits high catalytic activity in the HER with a low overpotential of 55 mV at a current density of 10 mA cm −2 in an acidic solution. Moreover, under 1 M KOH electrolyte, an overpotential of 187 mV is required in the HER over the catalyst to arrive 10 mA cm −2 and an overpotential of 289 mV is achieved in the OER at the same current density. The superior HER and OER activities of the PdNi/CNFs are attributed to the synergistic effects of the PdNi alloy nanoparticles (NPs) assembled on the CNFs. This work provides a simple route for synthesizing highly efficient bifunctional electrocatalysts from 3d transition metals and a small amount of noble metals for hydrogen and oxygen evolution reactions. [ABSTRACT FROM AUTHOR]

Fe incorporated Ni-based electrocatalysts have emerged as one of the most active oxygen-evolving catalysts under alkaline conditions and deciphering the effect of iron incorporation in enhancing the activity is challenging but critical for the catalyst design. Herein, the as-prepared nanocube Ni-based catalysts underwent a reconstruction process and transformed from γ-NiOOH to β-NiOOH structure by iron incorporation under the applied bias, which was confirmed by in-situ Raman measurement. According to the methanol oxidation current response difference, the hydroxyl adsorption intensity was proposed to be regulated by iron incorporation and the rate-determining step would be the formation of *OOH for Fe-doped β-NiOOH, which was further supported by DFT calculation. This work reveals the effect of iron-doped on the phase structure transform and the regulation of intermediate species elaborately and offers new insight on the understanding of the activity origins for NiFe-based catalysts. [Display omitted] • Potential-induced reconstruction process from γ-NiOOH to β-NiOOH structure by iron incorporation under applied bias. • The Fe-doped β-NiOOH exhibited an overpotential of 247 mV at 10 mA·cm−2 and a Tafel slope of 40.15 mV·dec−1. • The surface coverage of *OH varies in the trend: NiOOH > Fe-doped β-NiOOH > FeOOH. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical activation was employed to prepare Pt/PtTe x heterojunctions. • CV method and DFT calculation both reveal the change of intermediates adsorption. • Pt/PtTe x interface structure reduces H* adsorption and enhances OH* adsorption. • Pt/PtTe x NRs show significantly improved acidic and alkaline HER activity. Increasing OH* adsorption to promote water dissociation while reducing H* adsorption to accelerate hydrogen generation kinetics is an effective solution to further improve the HER activity of Pt-based catalysts. Herein, we have successfully constructed a Pt/PtTe x heterogeneous catalysis interface by electrochemical activation of PtTe 2 nanorods (NRs). The reduction of H* adsorption and significant increase of OH* adsorption was observed on Pt/PtTe x heterojunction via cyclic voltammetry method. Theoretical calculations indicate that Gibbs free energy change (ΔG) of H* is closer to 0.00 eV and ΔG of OH* decreased from 1.36 eV of Pt (111) to −0.40 eV of Pt/PtTe x , which reinforces the experimental results. The rational modulation of adsorbed intermediates endows Pt/PtTe x NRs with exceptionally lower Tafel slopes of 16 and 23 mV dec−1 in 0.5 M H 2 SO 4 and 1.0 M KOH electrolytes, which is among the best reported HER electrocatalysts. [ABSTRACT FROM AUTHOR]

Delicate construction of sophisticated bimetallic nanostructures provides a favorable way to boost the efficiency of bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which is critical to the fabrication of rechargeable Zn-air batteries. Herein, hetero-structured Cu/Co 93 Cu 7 nanoparticles confined inside N-doped carbon nanocages (denoted as Cu/Co 93 Cu 7 @NC NCs) are fabricated through a facile "MOF-in situ-reduction and in situ-growth-MOF" strategy. Benefiting from the unique hollow architecture and superior intrinsic activity of the optimized interfaces, the as-prepared catalyst displays an appealing electrocatalytic performance including a positive half-wave potential (E 1/2) of 0.88 V for ORR and a low OER overpotential of 262 mV at 10 mA cm−2. Theoretical calculations further disclose the key role of the rationally designed Co/Cu/N-doped carbon heterostructures, which significantly reduces the energy barrier for *OOH formation and eventually promotes the ORR. Rechargeable Zn-air batteries assembled with the Cu/Co 93 Cu 7 @NC NCs exhibit a large specific capacity of 884.9 mAh g Zn −1 and a maximum power density of 225.9 mW cm−2. Moreover, the assembled batteries are stable for 1000 h during the long-term charge and discharge cycling, demonstrating the great promise for practical applications. [Display omitted] • An efficient Cu/Co 93 Cu 7 @NC NCs catalyst is designed for ORR and OER. • The hollow architecture enhances the electrocatalytic kinetics. • DFT verifies that N–C, Cu and Co cooperatively improve the intrinsic activity. • The as-assembled Zn-air batteries exhibit excellent activity and durability. [ABSTRACT FROM AUTHOR]

A bifunctional Co 2 (OH) 3 Cl/FeOOH electrode used in a 10*10 cm2 membrane electrode assembly for a cyclohexanone production rate of 3.44 g/h and electricity saved about 0.24 kWh/m3 (H 2). The carbon free-radical reaction pathways for cyclohexanol electrooxidation on CoII/CoIII redox active species was elaborately elucidated. [Display omitted] • A voltage of 1.46 V at 10 mA·cm−2 was required for H 2 and CXO product. • In-situ measurements and DFT calculations elucidated the synergistic effect. • Carbon free-radical pathway for CXL oxidation on CoII/CoIII redox active species. • A CXO yield was 3.44 g/h and electricity saved about 0.24 kWh/ m3 (H 2) in MEA. Replacing oxygen evolution reaction with the more thermodynamically favorable organics oxidation reaction is crucial to reduce the required voltage of overall water splitting. Herein, Co 2 (OH) 3 Cl/FeOOH nanosheets are served as both cathode and anode for the concurrent high purity hydrogen generation and high value-added cyclohexanone productions. Thanks to the wondrous synergistic effect between Co 2 (OH) 3 Cl and FeOOH, for Co 2 (OH) 3 Cl acted as the optimal catalytic sites for cyclohexanol oxidization and FeOOH accelerated the reaction rates by reducing the charge transfer resistance, the two-electrode configuration only required a voltage as low as 1.46 V at 10 mA·cm−2 for cathode H 2 and anode cyclohexanone. Moreover, by further scaling up the configuration into the 10*10 cm2 anion membrane electrode assembly reactor, a cyclohexanone production rate of 3.44 g/h and the electricity saved about 0.24 kWh/ m3 (H 2) were achieved. In addition, the reaction pathways, the C–H bond cleaves first, and then the intermediate carbon free radical is dehydrogenated to generate cyclohexanone on CoII/CoIII redox, was elucidated elaborately. This work offers an approach to actuate effective transformation of organics with high selectivity and industrial practicability under ambient conditions powered by renewable energy. [ABSTRACT FROM AUTHOR]

The electron-rich interface of Cu-Co heterostructure nanoparticle an realize the effective separation of photogenerated charge and hole, accelerate the transfer of photogenerated charges, which is a stable and efficient cocatalyst for photocatalytic hydrogen evolution reaction. [Display omitted] • Carbon-coated Cu-Co alloy nanoparticles (CuCo@C) nanoparticles are fabricated. • The bimetallic CuCo has a heterogeneous structure with abundant Cu-Co interfaces. • A large number of photogenerated electrons can be collected at the Cu-Co interface. • The CuCo@C is a high-performance cocatalyst for photocatalytic H 2 evolution. Heterogeneous nano-metal structures are widely used in the field of photocatalysis as an efficient cocatalyst, but the structure–activity relationship has not been elucidated clearly. In this work, a classical CuCo@C nanoparticle with a core of bimetallic CuCo and a carbon shell was used as a cocatalyst to explore and reveal the mechanism of interfacial effect for enhanced photocatalytic hydrogen evolution. It was found that the bimetallic CuCo had a heterogeneous structure with abundant Cu-Co interfaces. The desirable visible-light-driven photocatalytic hydrogen evolution rate of CuCo@C/g-C 3 N 4 was much higher than that of Cu@C/g-C 3 N 4 , Co@C/g-C 3 N 4 , and superior to that of the control group loaded with 1 wt% Pt (Pt/g-C 3 N 4). According to the experimental characterizations and density functional theory calculations, electrons were enriched at the Cu-Co interface, which can promote the electron-hole pairs separation and accelerate charge transfer of the g-C 3 N 4 host photocatalysts. On the other hand, the surface carbon layer and Cu-Co interface modulated the H adsorption free energy on the CuCo@C, which was favorable for hydrogen evolution. It is conceivable that further investigating and tuning different metal interfaces will facilitate the large-scale application of bimetallic cocatalysts. [ABSTRACT FROM AUTHOR]

A novel hierarchical structure was fabricated by integrating gold nanoparticles (AuNPs) on nitrogen-doped carbon nanorods encapsulating carbon nanofibers (AuNPs@NCNRs/CNFs), and the composite was demonstrated as an electrocatalyst for the hydrogen evolution reaction (HER). First, polyaniline nanorods (PNRs) were grown on the surfaces of the CNFs, and the PNR/CNF hybrids were then decorated with small, well-dispersed and size-controlled AuNPs. The morphology, structure and chemical states of the AuNPs@NCNRs/CNFs hybrids were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The AuNPs@NCNRs/CNFs can be used directly as an electrode and exhibit good HER activity with a relatively low onset potential of 126 mV, a Tafel slope of 93 mV dec −1 and remarkable durability in 0.5 M H 2 SO 4 . The enhancement of the HER activity could be attributed to the synergetic effect between the nitrogen-doped carbon fibers and the AuNPs. [ABSTRACT FROM AUTHOR]