Intrinsic Hydrogen Evolution Reaction Research Articles

Nanocrystalline transition metal tetraborides as efficient electrocatalysts for hydrogen evolution reaction at the large current density

While great efforts have been made to improve the electrocatalytic activity of existing materials toward hydrogen evolution reaction (HER), it is also importance for searching new type of nonprecious HER catalysts to realize the practical hydrogen evolution. Herein, we firstly report nanocrystalline transition metal tetraborides (TMB4, TM=W and Mo) as an efficient HER electrocatalyst has been synthesized by a single-step solid-state reaction. The optimized nanocrystalline WB4 exhibits an overpotential as low as 172 mV at 10 mA/cm2 and small Tafel slope of 63 mV/dec in 0.5 M H2SO4. Moreover, the nanocrystalline WB4 outperforms the commercial Pt/C at high current density region, confirming potential applications in industrially electrochemical water splitting. Theoretical study reveals that high intrinsic HER activity of WB4 is originated from its large work function that contributes to the weak hydrogen-adsorption energy. Therefore, this work provides new insights for development of robust nanocrystalline electrocatalysts for efficient HER.

Oxophilic gallium single atoms bridged ruthenium clusters for practical anion-exchange membrane electrolyzer

The development of highly efficient and durable alkaline hydrogen evolution reaction (HER) catalysts is crucial for achieving high-performance practical anion exchange membrane water electrolyzer (AEMWE) at ampere-level current density. Herein, we report a design concept by employing Ga single atoms as an electronic bridge to stabilize the Ru clusters for boosting alkaline HER performance in practical AEMWE. Experimental and theoretical results collectively reveal that the bridged Ga sites trigger strong metal-support interaction for the homogeneous distribution of Ru clusters with high density, as well as optimize the Ru–H bond strength due to the electron transfer between Ru and Ga for enhanced intrinsic HER activity. Moreover, the oxophilic Ga sites near the Ru clusters tend to adsorb the hydroxyl species and accelerate the water dissociation for sufficient proton supplement in an alkaline medium. The Ru–GaSA/N–C catalyst exhibits a low overpotential of 4 ± 1 mV (10 mA cm−2) and high mass activity of 9.3 ± 0.5 A mg−1Ru at −0.05 V vs RHE. In particular, the Ru–GaSA/N–C-based AEMWE in 1 M KOH delivers a voltage of only 1.74 V to reach an industrial current density of 1 A cm−2, and can steadily operate at 1 A cm−2 for more than 170 h.

Cation/anion-doping induced electronic structure modulation of CoMoO4 for enhanced hydrogen evolution

The design and fabrication of high-performance, inexpensive and durable electrocatalyst toward hydrogen evolution reaction (HER) is supremely significant for alleviating energy crisis and environmental concerns, but still remaining challenging. Herein, we develop an experimental work based on etching and reduction strategy to reveal the remarkable effect of cation/anion co-doping in CoMoO4 on its intrinsic HER activity. The CoMoO4 with Fe and B incorporation (Fe/B-CoMoO4) exhibits a current density of 10 mA cm−2 with strikingly low potential of 38 mV coupling with Tafel slope of 51 mV dec-1, and manifesting a robust durability for 100 h with no attenuation, which is comparable to the state-of-the-art commercial Pt/C catalyst. The collective experimental and theoretical findings concomitantly illustrate that the enhanced performances are due to the strong synergistic effect resulting from the co-doping of Fe and B, which plays a pivotal role in finely tuning the electronic structure of CoMoO4, further optimizing the adsorption free energy of H intermediates and shifting the center of the d-band of Fe/B-CoMoO4 away from the Fermi level. This fantastic work highlights the critical role of foreign element incorporating for optimizing electronic structure of transition metal oxides toward HER, and offers valuable guiding principles for rational design of more efficient energy conversion devices.

Hierarchical NiCo2Se4 Arrays Composed of Atomically Thin Nanosheets: Simultaneous Improvements in Thermodynamics and Kinetics for Electrocatalytic Water Splitting in Neutral Media.

The inefficiency of electrocatalysts for water splitting in neutral media stems from a comprehensive impact of poor intrinsic activity, a limited number of active sites, and inadequate mass transport. Herein, hierarchical ultrathin NiCo2Se4 nanosheets are synthesized by the selenization of NiCo2O4 porous nanoneedles. Theoretical and experimental investigations reveal that the intrinsic hydrogen evolution reaction (HER) activity primarily originate from the NiCo2Se4, whereas the high oxygen evolution reaction (OER) performance is related to the NiCoOOH due to the structural reconstruction. The abundant Se and O vacancies introduced by atomically thin nanostructure modulate the electronic structure of NiCo2Se4 and NiCoOOH, thereby improving the intrinsic HER and OER activities, respectively. COMSOL simulation demonstrate the edges of extended nanosheets from the main body significantly promote the charge aggregation, boosting the reduction and oxidation current during HER/OER process. This charge aggregation effect notably exceeds the tip effect for the nanoneedle, highlighting the unique advantage of the hierarchical nanosheet structure. Benefiting from abundant vacancies and unique nanostructure, the hierarchical ultrathin nanosheet simultaneously improve the thermodynamics and kinetics of the electrocatalyst. The optimized samples display an overpotential of 92mV for HER and 214mV for OER at 100mA cm-2, significantly surpassing the performance of currently reported HER/OER catalysts in neutral media.

Nanoporous cobalt-doped AlNi3/NiO architecture for high performing hydrogen evolution at high current densities

Engineering platinum-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is essential for electrochemical hydrogen production. In this paper, we report the synthesis of cobalt-doped AlNi3/NiO (Co-AlNi3/NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi3/NiO can accelerate water adsorption / dissociation and optimize adsorption–desorption energies of H* intermediates, thus improving the intrinsic HER activity. Both the introduction of Co and Al can efficiently ameliorate the electronic density around Ni sites of NiO and AlNi3, which can effectively reduce the energy barrier towards Volmer–Heyrovsky reaction and thus synergistically promote the hydrogen evolution. Benefiting from the large electrochemical active surface area, high electrical conductivity and electronic effect, the nanoporous Co-AlNi3/NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm−2 in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi3/NiO catalyst can operate continuously over 1000 h at high current densities with a robust stability. This work provides a new vision for the development of low-cost and efficient electrocatalysts for energy conversion applications.

Pt nanoparticles anchored by oxygen vacancies in MXenes for efficient electrocatalytic hydrogen evolution reaction.

The improvement of the hydrogen evolution reaction (HER) performance of nanomaterials is associated with the interfacial synergistic interaction and their hydrogen adsorption kinetics. Nevertheless, it is still a challenge to accelerate the proton transfer and optimize the HER kinetics by constructing Pt-supported heterostructures based on the hydrogen spillover phenomenon. Herein, oxygen vacancies on the surface of MXene nanosheets were constructed via a high-temperature annealing method, which was employed to anchor/stabilize Pt nanoparticles and fabricate a Pt/MXene heterostructure. EPR and XPS analyses verified the presence of oxygen vacancies, which could enhance the intrinsic HER activity of the MXene. The HER catalytic performance was investigated by taking into account the surface structure of the MXene affected by the annealing temperature, the concentration of Pt and the number of deposition cycles. Electrochemical results showed that Pt/MXene with higher utilization of Pt was obtained at 900 °C and 0.05 mgPt mL-1. The 0.05-Pt/MXene-900 obtained at deposition of 60 cycles in 0.5 M H2SO4 solution exhibited the optimized HER activity. The overpotential was 22 mV at a current density of 10 mA cm-2 and the Tafel slope was 42.41 mV dec-1. Furthermore, the accelerated HER kinetics was mainly due to the electron trapping ability of the MXene, small particles of Pt, as well as the enhanced charge transfer between the oxygen vacancies of the MXene and Pt. This strategy for constructing Pt-supported heterostructures based on the vacancy anchoring effects provides new ideas for the design of well-defined electrocatalysts toward the HER.

Excellent catalytic activity of Pt nanoparticles supported on defective TiO2/graphite for hydrogen evolution reaction

Exploring effective electrocatalysts based on noble metal for hydrogen evolution reaction (HER) is an attractive topic in the renewable energy field. Herein, the Pt–based nanocomposites, called Pt@TiO2–VO/C, were successfully fabricated by using a photochemical reduction method. The layered Ti3C2Tx−MXene powders were used as precursor to prepare TiO2 nanotube/C nanocomposites. The Pt nanoparticles (Pt NPs) with the diameter of 2 nm were anchored on the defective TiO2 nanotubes (TiO2 NTs). The Pt@TiO2–VO/C electrocatalysts demonstrate superior performance for HER in an acid electrolyte, with overpotentials as low as 47 and 86 mV at the current densities of 10 and 100 mA cm−2, respectively. The intrinsic HER activity with respect to electrochemical surface area of Pt@TiO2–VO/C is superior than Pt/C. The Pt@TiO2–VO/C catalysts also exhibit excellent durability. Density functional theory calculations were performed to investigate the electronic structure and HER activity of TiO2–VO supported Pt cluster. The excellent performance of Pt@TiO2–VO/C is primarily due to the strong interactions between Pt NPs and defective TiO2 NTs, known as strong metal–support interactions (SMSIs). The presence of Ti3+ ions and oxygen vacancies in TiO2 NTs facilitates the charge transfer from TiO2 NTs to Pt NPs, thereby regulating the band filling of Pt NPs. Our work provides a promising pathway to build nanocomposite catalysts constructed by MXene–derived transition–metal oxides and precious metals.

Hydrogen Evolution Reaction on Ultra-Smooth Sputtered Nanocrystalline Ni Thin Films in Alkaline Media-From Intrinsic Activity to the Effects of Surface Oxidation.

Highly effective yet affordable non-noble metal catalysts are a key component for advances in hydrogen generation via electrolysis. The synthesis of catalytic heterostructures containing established Ni in combination with surface NiO, Ni(OH)2, and NiOOH domains gives rise to a synergistic effect between the surface components and is highly beneficial for water splitting and the hydrogen evolution reaction (HER). Herein, the intrinsic catalytic activity of pure Ni and the effect of partial electrochemical oxidation of ultra-smooth magnetron sputter-deposited Ni surfaces are analyzed by combining electrochemical measurements with transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. The experimental investigations are supplemented by Density Functional Theory and Kinetic Monte Carlo simulations. Kinetic parameters for the HER are evaluated while surface roughening is carefully monitored during different Ni film treatment and operation stages. Surface oxidation results in the dominant formation of Ni(OH)2, practically negligible surface roughening, and 3-5 times increased HER exchange current densities. Higher levels of surface roughening are observed during prolonged cycling to deep negative potentials, while surface oxidation slows down the HER activity losses compared to as-deposited films. Thus, surface oxidation increases the intrinsic HER activity of nickel and is also a viable strategy to improve catalyst durability.

Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance.

Efficient cathodes for the hydrogen evolution reaction (HER) in acidic water electrolysis rely on the use of expensive platinum group metals (PGMs). However, to achieve economically viable operation, both the content of PGMs must be reduced and their intrinsically strong H adsorption mitigated. Herein, we show that the surface effects of hydrogenated TiO2 nanotube (TNT) arrays can make osmium, a so far less-explored PGM, a highly active HER electrocatalyst. These defect-rich TiO2 nanostructures provide an interactive scaffold for the galvanic deposition of Os particles with modulated adsorption properties. Through systematic investigations, we identify the synthesis conditions (OsCl3 concentration/temperature/reaction time) that yield a progressive improvement in Os deposition rate and mass loading, thereby decreasing the HER overpotential. At the same time, the Os particles deposited by this procedure remain mainly sub-nanometric and entirely cover the inner tube walls. An optimally balanced Os@TNT composite prepared at 3 mM/55 °C/30 min exhibits a record low overpotential (η) of 61 mV at a current density of 100 mA cm-2, a high mass activity of 20.8 A mgOs-1 at 80 mV, and a stable performance in an acidic medium. Density functional theory calculations indicate the existence of strong interactions between the hydrogenated TiO2 surface and small Os clusters, which may weaken the Os-H* binding strength and thus boost the intrinsic HER activity of Os centers. The results presented in this study offer new directions for the fabrication of cost-effective PGM-based catalysts and a better understanding of the synergistic electronic interactions at the PGM|TiO2 interface.

Solid-Electrolyte Interphase Chemistries Towards High-Performance Aqueous Zinc Metal Batteries.

Aqueous zinc metal batteries (AZMBs) are deemed a promising technology for electrochemical energy storage due to their high safety, low cost, and high energy density. However, AZMBs still suffer from severe side reactions, including Zn dendrite formation and intrinsic hydrogen evolution reaction. In contrast to the solid-electrolyte interphase (SEI) layer that stabilizes Li/Na/K metal anodes in organic electrolytes, it is difficult to form an SEI layer on the Zn surface because of the difficulty in decomposing the salt anions within the narrow electrochemical potential window of water. A team from the University of Adelaide reports a novel pure or hybrid electrolyte with H2 O by using dimethyl methylphosphonate (DMMP) as solvent or co-solvent to construct a uniform and stable phosphate-based SEI layer (ZnP2 O6 and Zn3 (PO4 )2 ). As a result, high Coulombic efficiencies and improved capacity retentions are obtained.

Solid‐Electrolyte Interphase Chemistries Towards High‐Performance Aqueous Zinc Metal Batteries

AbstractAqueous zinc metal batteries (AZMBs) are deemed a promising technology for electrochemical energy storage due to their high safety, low cost, and high energy density. However, AZMBs still suffer from severe side reactions, including Zn dendrite formation and intrinsic hydrogen evolution reaction. In contrast to the solid‐electrolyte interphase (SEI) layer that stabilizes Li/Na/K metal anodes in organic electrolytes, it is difficult to form an SEI layer on the Zn surface because of the difficulty in decomposing the salt anions within the narrow electrochemical potential window of water. A team from the University of Adelaide reports a novel pure or hybrid electrolyte with H2O by using dimethyl methylphosphonate (DMMP) as solvent or co‐solvent to construct a uniform and stable phosphate‐based SEI layer (ZnP2O6 and Zn3(PO4)2). As a result, high Coulombic efficiencies and improved capacity retentions are obtained.

Advanced Pt-based electrocatalysts for the hydrogen evolution reaction in alkaline medium.

Water electro-splitting driven by renewable energy is significant in energy conversion for the development of hydrogen energy sources. The hydrogen evolution reaction (HER) directly generating hydrogen products occurs in cathode catalysis. Over the years, significant progress has been made to boost the HER efficiency by exploratively designing highly active and economical Pt-based electrocatalysts. However, there are still some urgent problems to be solved for Pt-based HER catalysts in more economical alkaline electrolytes, such as the slow kinetics caused by additional hydrolysis dissociation steps, which greatly hinders the practical application. This review systematically summarizes several strategies for optimizing alkaline HER kinetics and provides direct guidelines for the design of highly active Pt-based electrocatalysts. Specifically, the intrinsic HER activity in alkaline water electrolysis can be boosted by accelerating the water dissociation, optimizing the hydrogen binding energy or modulating the spatial dimensions of the electrocatalyst based on the HER mechanism. Finally, we prospect the challenges for the alkaline HER on novel Pt-based electrocatalysts, including the active site study, the HER mechanism exploration and the extensible catalyst preparation technologies.

A novel 0D/2D/2D hetero-layered nitrogen-doped graphene/MoS2 architecture for catalytic hydrogen evolution reaction

• A hybrid of Ni@N-Gr with exfoliated MoS 2 is reasonably designed and synthesized. • Ni@N-Gr/MoS 2 provides a stimulating insight to form non-precious metal doping onto layered 2D/2D hetero-assembly. • The hybrid has high electronic conductivity and rich exposed active sites. • Ni@N-Gr/MoS 2 exhibits superior and durable electrocatalytic performance in acidic medium. Two-dimensional (2D) layered molybdenum disulfide (MoS 2 ) has emerged as a promising Pt-substituting electrocatalyst for the hydrogen evolution reaction (HER) recently. Despite the ever-growing interest in these MoS 2 based-materials, their catalytic performance is still far from satisfactory due to the nature of the inactive basal plane and poor conductivity. This work presents a novel nickel@nitrogen‐doped graphene@MoS 2 (Ni@N-Gr/MoS 2 ) triad heterostructure for catalytic HER. The as-synthesized Ni@N-Gr/MoS 2 assembly exhibits high intrinsic HER activity with a low overpotential of 270 mV at 10 mA cm −2 , an onset overpotential of 60 mV, a small Tafel slope of 56 mV dec −1 , and robust stability in 0.5 M H 2 SO 4 . The notable activity of the Ni@N-Gr/MoS 2 composites is attributed to two main causes (i) presence of further catalytic active sites due to the incorporation of Ni@N-Gr in the basal plane of MoS 2 (ii) improvement of the conductivity due to nitrogen-doped Gr; where a fast electron transfer takes place from Ni@N-Gr core to MoS 2 during HER. Our novel-hybrid strategy is promising as an electrochemical platform in industrial hydrogen production and hence can stimulate further structural realizations to employ other metal species.

Ultrathin Two-Dimensional Polyoxometalate-Based Metal-Organic Framework Nanosheets for Efficient Electrocatalytic Hydrogen Evolution.

The rational design of 2D polyoxometalate-based metal-organic framework (POMOF) nanosheets on a conductive substrate as a self-supporting electrode is highly attractive but a great challenge. Herein is the first demonstration of POMOF nanopillar arrays consisting of 2D nanosheets as a self-supported electrode for the hydrogen evolution reaction (HER) in acidic conditions. Single-crystal X-ray analysis reveal that our as-prepared 2D [Co2(TIB)2(PMo12O40)]·Cl·4H2O [named CoMo-POMOF; TIB = 1,3,5-tris(1-imidazoly)benzene] crystalline materials are connected by Co-α-Keggin polymolybdate units act as secondary building blocks and TIB as the organic ligands. The 2D CoMo-POMOF nanosheets were successfully arrayed on a conductive nickel foam substrate by a facile CoO nanorod template-assisted strategy. Remarkably, the CoMo-POMOF nanopillar arrays demonstrate superior electrocatalytic performance toward the HER with an overpotential of 137 mV and Tafel slope of 59 mV dec-1 at 10 mA cm-2, which are comparable to those of state-of-the-art POMOF-based electrocatalysts. Density-functional theory (DFT) calculations demonstrate that the exposed bridging oxygen active sites (Oa) of Co-α-Keggin polymolybdate units in CoMo-POMOF optimize the Gibbs free energy of H* adsorption (ΔGH* = -0.11 eV) and increase the intrinsic HER activity.

Re nanoflower-decorated carbon cloth for pH-universal hydrogen evolution reaction: Unveiling the intrinsic electrocatalytic activity of metallic Re

The hydrogen evolution reaction (HER) is one of the primary routes for clean hydrogen energy production to replace fossil fuels. However, the lack of cost-effective electrocatalysts hinders its practical implementation. Re, which is considerably less expensive than Pt, has recently emerged as an electrocatalyst owing to its high HER activity over a wide pH range. However, HER processes of Re have been studied primarily through spectroscopy, with little theoretical interpretation to explain the intrinsic HER activity of Re. Additionally, it is necessary to develop antioxidative Re electrocatalysts to prevent hydrogen intercalation, and to suppress catalyst aggregation to ensure long-term stability. In this work, a theoretical analysis was first conducted to investigate the free energy of each HER intermediate and demonstrate high performance of Re. Then, a novel free-standing electrocatalyst consisting of Re nanoflowers (NFs) grown in-situ on a carbon cloth (CC) was synthesized (ReNF@CC) via a hydrothermal method followed by thermal annealing. The Re NFs homogeneously grown on the CC surface effectively suppressed self-aggregation to preserve abundant active sites, and the direct coupling of Re NFs enhanced the conductivity and physical/electrochemical stability to prevent their detachment from the CC during operation. A high HER performance was obtained with low overpotentials of 103, 115, and 75 mV at 10 mA cm−2 in 0.5 M H2SO4, 1 M PBS, and 1 M KOH, respectively; additionally, a superior durability with respect to commercial Pt/C was achieved. Overall, this study offers a versatile and universal strategy for highly efficient water electrolysis in different media.

Effect of Nitrogen Atom Introduction on the Photocatalytic Hydrogen Evolution Activity of Covalent Triazine Frameworks: Experimental and Theoretical Study.

The construction of high-performance photocatalyst has always been explored. Covalent organic frameworks (COFs), especially keto-amine-linked COFs, have many advantages, such as adjustable bandgaps, π-π stacking structure, excellent response ability to visible light, high specific surface area, high mobility of carrier carriers, good physical and chemical stability, and so on, showing strong potential applications in photocatalytic solar energy conversion and hydrogen production. Two analogous covalent triazine frameworks (CTFs), T3H-CTF and T3N-CTF, have been synthesized via Schiff-base condensation reactions between 2,4,6-trihydroxybenzene-1,3,5-tricarbalehyde (MOP) and the corresponding triazine-based aromatic amines under solvothermal condition. For T3N-CTF, the peripheral aromatic linker to the central triazine unit was the pyridine unit, instead of the benzene unit in the T3H-CTF unit. T3N-CTF had a hydrogen production rate (HPR) of 6485.05 μmol g-1 h-1 , much higher than that of T3H-CTF (2028.06 μmol g-1 h-1 ). Accordingly, T3N-CTF had a much higher apparent quantum yield (AQY) of 12.2 % than that of T3H-CTF (4.12 %) at 405 nm. The experimental and theoretical results showed that the extended light absorption range, enlarged surface area, and enhanced separation and transportation efficiencies of charge carriers of T3N-CTF compared with T3H-CTF were uniformly induced by the introduction of peripheral nitrogen atoms into the skeleton of former CTF, which eventually boosted the visible-light induced hydrogen evolution reaction (HER). The work suggests a new method for enhancing the intrinsic HER activity by modulating the electronic features of the conjugated COFs by the introduction of pyridinic N atoms.

Multi-interfacial Ni/Mo2C ultrafine hybrids anchored on nitrogen-doped carbon nanosheets as a highly efficient electrocatalyst for water splitting

Interfacial engineering in the rapid development of high-performance electrocatalysts for water splitting has been explored as a promising strategy to improve catalytic performance due to the tunable free energy of reaction intermediates on the interfacial compositions. Here, multiple-interfacial Ni/molybdenum carbide hybrid nanoparticles embedded in N-doped carbon nanosheets (Ni/Mo2C@NC) electrocatalyst were fabricated via a solid-state co-reduction method. The as-synthesized catalyst exhibits excellent hydrogen evolution reaction (HER) activity with an overpotential of 91 mV at 10 mA/cm2 and a Tafel slope of 74 mV/dec in alkaline solution, and outstanding stability owing to the high conductivity, abundant interfacial active sites, and synergistic effect between Ni and Mo2C nanoparticles. This electrocatalyst as bifunctional electrode possesses an applied voltage of 1.64 V at 10 mA/cm2 and long-term durability in an electrolysis cell. Moreover, density functional theory calculations reveal that the electron transfer across Ni/Mo2C heterointerfaces could optimize the water adsorption/dissociation and H adsorption/desorption capacities, thereby boosting the intrinsic HER activity.

Regulating the electronic structure of cobalt phosphide via dual-metal doping engineering to trigger efficient hydrogen evolution

Exploration of earth-abundant, low cost, and versatile catalysts with Pt-like performance for electrochemical water splitting holds practical significance for clean energy shortage and environmental pollution. However, manipulating the electronic structure and relevant physical properties of the catalysts is crucial in promoting their hydrogen evolution reaction (HER) performance but still a formidable challenge. In this work, we report a self-supported dual-metal doped on CoP3 nanowire arrays (NAs) and grown on carbon fiber cloth (Ni,Mn-CoP3 NAs) for alkaline HER. The optimized catalyst exhibits superior electrocatalytic activity, giving a low overpotential of 24 mV at 10 mA cm−2 with a small Tafel slope of 41 mV dec−1 and can sustain for 24 h, which is superior to the commercial Pt/C catalysts at a large current density. On the basis of systematic experiments and density functional theory calculations, the synergistic regulation of dual-metal doping can re-form the electronic structure so as to enhance the electrical conductivity, improve the intrinsic HER activity, and increase the electrochemical surface area of CoP3. This work points out avenues in the reasonable design and development of dual-metal doped transition-metal phosphides as highly active, durable, and economically viable catalysts for various catalytic reactions.

BiO 2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO 2 Reduction to Formate

BiO _2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO ₂ Reduction to Formate

Integrating CoNiSe2 Nanorod-arrays onto N-doped Sea-sponge-C spheres for highly efficient electrocatalysis of hydrogen evolution reaction

A key issue for enhancing performance of hydrogen evolution reaction (HER) by utilizing seawater for sustainable clean energy is to develop a highly efficient, stable and economical electrocatalyst. Herein, a uniquely hierarchical nanostructure of CoNiSe2 nanorod-arrays (NRAs) integrated onto N-doped sea-sponge-carbon spheres (CoNiSe2/N-SSCSs) was designed and synthesized using successive ultrasonic spray pyrolysis (USP) and solvothermal - hydrothermal selenization (SHS) processes. Attributed to intrinsic HER activity of CoNiSe2 NRAs together with effective electron-transfer and ion-diffusion pathways of N-SSCSs, the CoNiSe2/N-SSCSs nanocomposites exhibited highly stable HER electrocatalytic performances in both alkaline electrolytes and alkaline simulated seawater. The required overpotential is as low as 88 mV with a Tafel slope of 83 mV dec−1 at 10 mA cm−2 in 1.0 M KOH, which are comparable to the electrode of commercial Pt/C (η10 = 35 mV &b = 58 mV dec−1).