High Hydrogen Evolution Reaction Activity Research Articles

Iron phosphide nanoparticles anchored on 3D nitrogen-doped graphene as an efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Electrocatalysts play a crucial role in hydrogen evolution reaction (HER), facilitating a clean and sustainable generation of hydrogen energy. To promote the HER process, it is imperative to employ highly efficient, stable, and cost-effective electrocatalysts. This research focuses on the design of iron phosphide nanoparticles anchored onto a porous three-dimensional nitrogen-doped graphene (FeP@3DNG). The porous framework of 3DNG serves a multifaceted purpose: it prevents the aggregation of FeP nanoparticles during phosphidation, safeguards the FeP electrocatalyst from oxidation during the HER, and simultaneously enhances electrical conductivity and stability. Notably, the FeP@3DNG nanocomposite demonstrated the efficient activity and highest HER activity with an overpotential of 76 mV to achieve 10 mA cm−2 and a small Tafel slope of 40.2 mV dec−1 as well as good long-term durability for 20 h in 1.0 M KOH solution. The high performance of the FeP@3DNG nanocomposite can be primarily corresponded to the synergistic effects of the highly active of FeP nanoparticles and advantages of porous three-dimensional graphene with excellent electrocatalytic activity, high specific surface area, and chemical stability, thus, resulting in the improvement the overall electrocatalytic activity.

Modulating the Electronic Structure of MnNi2S3 Nanoelectrodes to Activate Pyroptosis for Electrocatalytic Hydrogen-Immunotherapy.

Hydrogen (H2) therapy has demonstrated antitumor effect, but the therapeutic efficacy is restricted by the low solubility and nontarget delivery of H2. Electrolysis of H2O by electrocatalysts sustainably releases enormous amounts of H2 and inspires the precise delivery of H2 for tumor therapy. Herein, manganese-doped Ni2S3 nanoelectrodes (MnNi2S3 NEs) are designed for the electrocatalytic delivery of H2 and the activation of antitumor immunity to effectively potentiate H2-immunotherapy. Ni atoms featuring empty 3d orbitals reduce the initial energy barrier of the hydrogen evolution reaction (HER) by promoting the adsorption of H2O. Moreover, Mn atoms with different electronegativity modulate the electronic structure of Ni atoms and facilitate the desorption of the generated H2, thus enhancing the HER activity of the MnNi2S3 NEs. Based on the high HER activity, controllable delivery of H2 for electrocatalytic hydrogen therapy (EHT) is achieved in a voltage-dependent manner. Mechanistically, MnNi2S3 NE-mediated EHT induces mitochondrial dysfunction and oxidative stress, which subsequently activates pyroptosis through the typical ROS/caspase-1/GSDMD signaling pathway. Furthermore, MnNi2S3 NE-mediated EHT enhances the infiltration of CD8+ T lymphocytes into tumors and reverses the immunosuppressive microenvironment. This work demonstrates an electrocatalyst with high HER activity for synergistic gas-immunotherapy, which may spark electrocatalyst-based tumor therapy strategies.

Design of NiPS3/MoS2/rGO hybrid electrocatalyst for electrochemical hydrogen evolution

The design and development of efficient electrocatalysts for hydrogen evolution reaction is presently a pressing task to overcome future energy demands. In the present study a hybrid layered compound NiPS3/MoS2/rGO (NMR) is investigated as an electrocatalyst for hydrogen evolution reaction (HER). The metal trichalcogenidophosphates (MTPs), transition metal dichalcogenides and reduced graphene oxide materials based electrocatalysts are promising material for HER. The hybrid layered compound NMR displays good electrocatalytic activity in acidic medium in comparison to its counterparts MoS2/rGO and NiPS3/rGO with an overpotential and Tafel slope of 152 mV vs RHE and 75 mV/dec, whereas MoS2/rGO and NiPS3/rGO shows an overpotential of 206 mV and 223 mV vs RHE with a Tafel slope value of 146 mV/dec and 154 mV/dec respectively. The hybrid electrocatalyst exhibited high stability up to 1000 cycles with a stable current. The high HER activity of NMR is attributed to synergistic effect of electrocatalysts where P and S of NiPS3 acts as an appropriate hydrogen adsorption sites and catalytically active Mo edge sites of MoS2 with high charge carrier property of rGO contributed to enhanced hydrogen evolution reaction.

Harnessing the potential of MOF/Fe2O3 nanocomposite within polypyrrole matrix for enhanced hydrogen evolution

This study investigates the influence of pyrrole concentration and the addition of MIL53(Al)/Fe2O3 nanocomposite on the hydrogen evolution reaction (HER) activity of polypyrrole (PPy) electrocatalysts. Electrodeposition of PPy on a nickel (Ni) substrate was conducted using various pyrrole concentrations ranging from 0.01 M to 0.2 M, followed by evaluation through linear sweep voltammetry (LSV) experiments. Results indicated that PPy synthesized with 0.1 M pyrrole exhibited the highest HER activity, characterized by lower onset potential and higher current density. Additionally, the incorporation of MIL53(Al)/Fe2O3 nanocomposite into PPy coating enhanced electrode performance, evidenced by high charge transfer kinetics. Nyquist diagrams and electrochemical impedance spectroscopy (EIS) analysis confirmed accelerated electron transfer kinetics and lower charge transfer resistance for PPy@MIL53(Al)/Fe2O3 compared to Ni substrate. Despite a lower electrochemical double layer capacitance (Cdl), PPy@MIL53(Al)/Fe2O3 demonstrated enhanced catalytic activity, underscoring the importance of electrode morphology and active site characteristics. Furthermore, stability tests revealed consistent performance of PPy@MIL53(Al)/Fe2O3 over prolonged electrolysis periods, highlighting its potential for practical applications in hydrogen generation.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p-d Orbital Hybridization Effect with Ru.

Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Microwave‐Assisted PtRu Alloying on Defective Tungsten Oxide: A Pathway to Improved Hydroxyl Dynamics for Highly‐Efficient Hydrogen Evolution Reaction

AbstractPlatinum (Pt)‐based compounds are the benchmarked catalysts for hydrogen evolution reaction (HER) but exhibit slow kinetics in alkaline environments. The *OH accumulation on Pt surface can block active sites, affecting proton reduction and water re‐adsorption. Alloying Ruthenium (Ru) with Pt sites can significantly modulate the adsorption and desorption of water dissociation intermediates. Choosing suitable supports and utilizing metal‐support interaction (MSI) is crucial for active site optimization. PtRu alloy anchored on tungsten oxide (WO3) with rich oxygen vacancies (OV) is prepared through an ultrafast microwave‐assisted approach. Benefiting from the coupling effects between alloying and MSI, PtRu/WO3‐OV exhibits exceptionally high HER activity. In 1 m KOH, 1 m KOH + seawater, and 0.5 m H2SO4, it requires ultralow overpotentials of 9, 26, and 6 mV to achieve 10 mA cm−2, respectively. The designed catalyst surpasses commercial Pt/C in mass activity and demonstrates considerable potential for intermittent energy integration. Density functional theory reveals that alloying Ru with Pt sites significantly reduces the energy barrier of dissociating *OH, modulating blockage on the surface and then promoting the overall alkaline HER process. This study offers insights into the rapid synthesis of non‐carbon supported catalysts with Pt site modulation for alkaline hydrogen generation.

Nitrogen-doping engineering in two-dimensional transition-metal carbides for electrochemical hydrogen evolution

Developing electrocatalysts with the trade-off between overall electrocatalytic performance and economic cost towards hydrogen evolution reaction (HER) is crucial for producing green hydrogen fuels. Although theoretical studies have reported the potential of two-dimensional (2D) MXenes for the HER, their electrocatalytic performance is still unsatisfactory for the particular application due to their low intrinsic active and MXene stacking. To address this problem, we herein modify the electronic structure and increase the interlayer spacing between 2D Ti3C2Tx MXenes through ammonia (NH3)-assisted hydrothermal approach. The effect of synthesis temperature on the nitrogen doping mechanism and electrochemical behaviors for the HER is systemically explored. As a result, the nitrogen (N)-doped Ti3C2Tx MXene fabricated at 160 °C exhibits the highest HER activity among all 2D N-doped Ti3C2Tx nanosheets with the overpotential/Tafel slope of 186.91 mVRHE/115.94 mVRHE dec−1 in an acidic solution. Due to the synergistic contribution of nitrogen, the N-doped Ti3C2Tx-160 °C has mass activity of 337.95 mA mg−1 at 0.3 VRHE, being 27.50-fold higher than that of pristine Ti3C2Tx. This work indicated that heteroatom doping is a facile but efficient approach for modulating the electronic structure and intrinsic activity of MXene-based materials for electrochemical reactions.

Surface active sites and interphase engineering into metal oxide hydrates enabled by ions substitution for efficient water splitting

The expanding requirement of energy-effective and cost-efficient water electrolysis has prompted studies of earth-abundant metal-based electrocatalysts. In this study, we study the typical substitution strategies of cation (Pt) or anion (Se) for modifying surface active sites or interphase engineering to tune electronic structure of bimetallic nickel molybdenum oxide hydrates (NiMoO4·xH2O), thus effectively improving catalytic properties toward hydrogen evolution reaction (HER) or oxygen evolution reaction (OER). Result of the cation substitution achieves PtSA–NiMoO4·xH2O catalyst with abundant doped Pt single atoms on surface, which promotes high HER activity with a small overpotential of 73 mV at a current yield of 10 mA cm−2 in alkaline medium. Meanwhile, Se–NiMoO4·xH2O catalyst, an outcome of the anion substitution approach, has unique interfaces of NiSe-NiMoO4 heterostructure and thus exhibits a desired overpotential of only 297 mV for OER. The combination of PtSA–NiMoO4·xH2O(–)//Se–NiMoO4·xH2O(+) couple results in a two-electrode electrolyzer cell, which requires a small cell voltage of 1.48, 1.54 and 1.59 V to deliver a response of 10 mA·cm−2 at 75, 50 and 25 °C, respectively, along with negligible performance decay during 50 h operation. These results highlight the potential of our catalyst engineering strategies to achieve high-performance green hydrogen production.

Ni-Derived NiO Nanosphere Electrocatalyst for Hydrogen Evolution Reaction: The Effect of Synthesis Variables on Activity and Durability

Transition to a decarbonized society will rely on clean energy resources, in particular on "green” hydrogen—a renewable energy carrier that can be generated via water electrolysis [1]. Unlike proton exchange membrane water electrolyzers (PEMWE), anion exchange membrane water electrolyzers (AEMWEs) enable the use of earth-abundant transition metals in both the cathode and anode [2]. In addition, unlike liquid alkaline water electrolyzers, which use a highly concentrated alkaline media (6 M KOH), AEMWEs can operate with low-concentrated electrolyte, and even pure water [3]. Developing active and durable platinum group metal-free (PGM-free) electrocatalysts is crucial for the large-scale implementation of the AEMWE technology. Ni-based electrocatalysts have shown good activity towards the hydrogen evolution reaction (HER) in alkaline media [4]. Herein, carbon supported Ni-derived NiO nanosphere electrocatalysts are synthetized via a sol-gel method followed by thermal treatment under reducing atmosphere. We explored several synthesis parameters, i.e., Ni-to-carbon ratio, annealing temperature, and annealing time. We also investigated the impact of these synthesis variables on the HER activity in alkaline electrolyte. The catalysts were characterized by XRD, SEM, and EDS. The formation of Ni metal particles with a thin oxygen-rich layer on the surface was demonstrated by microscopy and crystallographic characterization. Following optimization, the HER overpotential of the best performing electrocatalyst at a current density of 10 mA cm−2 was reduced to ca. 130 mV. The catalyst durability was tested over 100 h in KOH solutions at different electrolyte concentrations using various testing protocols such as constant current hold and potential cycling. The catalyst showed higher HER activity (100 mV lower HER overpotential) and better durability behavior (0.15 mV/h lower degradation rate) compared to a commercial Ni supported Vulcan XC-72 electrocatalyst.

Electronic properties modulation for two-dimensional materials of boron phosphorus monolayer and derived single atom catalysts for the hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) is the core of the future renewable energy field and an important part of clean energy technology. It is urgent to find a noble metal free catalyst with high stability, good conductivity and economic efficiency for HER. Two-dimensional (2D) materials such as hexagonal boron nitride formed by the combination of B and N atoms of group III-V elements have been substantiated with significant electronic properties. We predict that 2D materials composed of B and P atoms of the same main group also have good electronic properties. This paper reports for the first time the application of two recent 2D boron phosphorus monolayer compounds (BS-B1P1 and PH-B1P1) as excellent single-atom catalysts (SACs) for HER. We have demonstrated that boron phosphorus compounds can obviously improve its electrical conductivity through single-atom transition metal (TM) doping through the density of state (DOS) calculations, which promises their applications in HER. Hence, an electrocatalyst is computer-aided designed with isolated TM single atom of 3d, 4d, and 5d supported on BS-B1P1 and PH-B1P1 to construct SACs with excellent HER performance. Interestingly, we find that the these SACs can show high HER activity in a wide pH-range. Among all SACs studied, Sc-, Ti-, Nb-, Ag-,and Hf-embedded BS-B1P1 have excellent catalytic activity in acidic conditions while Mn-, Ta-, Re-, Os-, Ir-, and Au-embedded BS-B1P1 show high catalytic activity in alkaline conditions. Mn@PH-B1P1 shows high catalytic activity only in acidic conditions. Especially, Tc@BS-B1P1 system exhibits promising catalytic activity, which owns high active in either neutral, acidic and alkaline conditions. Our work provides a highly active HER catalyst with pH regulation, providing a cost-effective alternative to traditional Pt-based catalysts for sustainable hydrogen extraction.

Enhanced hydrogen evolution catalysis on Rh nanoparticles with low loading on graphene nanoplatelets

Hydrogen evolution reaction (HER) was studied on rhodium nanoparticles electrochemically deposited under the same conditions on glassy carbon (Rh/GC) and on graphene nanoplatelets (Rh/GNPs) supports in 0.5 M H2SO4 solution. SEM revealed that the size of Rh nanoparticles ranged from 50 to 350 nm for Rh/GC and 20 to 70 nm for Rh/GNPs. XPS confirmed the presence of Rh in a low amount of 0.9 at% (6.8 wt%) in Rh/GC and 1.2 at% (8.6 wt%) in Rh/GNPs. The potentials for HER at 10 mA/cm2 are −0.076 V, −0.088, and −0.094 V, and the Tafel slopes are 42, 40, and 42 mV dec−1 for Rh/GNPs, Rh/GC, and Rh(poly), respectively. Moreover, the Rh/GNPs electrode exhibits a higher Rh turnover frequency (TOF) of 3.7 H2 sites−1 s−1 than Rh/GC whose TOF value is 2.9 H2 sites−1 s−1. An exceptionally high HER activity and stability of the Rh/GNPs indicates the strong influence of the GNPs support.

Two one‐dimensional cuprous iodide coordination polymers: Efficient and robust electrocatalysts for hydrogen evolution and glucose‐sensing

Development of efficient, low‐cost, robust, and structure tunability electrocatalysts for hydrogen evolution reaction (HER) is one of the main subjects of present study in renewable energies. In this work, two new cuprous iodide coordination polymers (Cu‐CPs) containing bisbenzimidazole‐derived ligand, namely, {[Cu2(L1)(μ2‐I)2]·DMF}n (1) and {[Cu(L2)0.5(μ2‐I)]·DMF} (2) (L1 = (2,2′‐(1,3‐propanediyl)‐6,6′‐bis(3‐methylpyridine)bis‐1,3‐benzimidazole); L2 = (2,2′‐(1,4‐butanediyl)‐7,7′‐bis(3‐methylpyridine)bis‐1,3‐benzimidazole); DMF = dimethyl formamide), were prepared under solvothermal conditions and structurally characterized. Single‐crystal structural analysis showed that although two Cu‐CPs have a one‐dimensional (1D) chain backbone structure, the coordination environment of cuprous is different. It is found that different coordination modes of ligands L1 and L2 lead to different coordination environments of central ions in two cuprous CPs. Electrocatalytic HER of modified electrodes (CP‐1~2/glassy carbon electrode [GCE]) prepared by coating the mixed solution of acetylene black, CPs 1–2, and Nafion on the surface of GCE was investigated in 0.5 M H2SO4 electrolyte. The HER measurements show that the overpotential η10293K of CP‐1~2/GCE positively shifted 113 and 74 mV compared with bare GCE (blank electrode, −930 mV), and the Tafel slope of bare/GCE and CP‐1~2/GCE were 298, 101, and 138 mV dec−1, respectively. The results indicate that CP‐1~2/GCE could effectively catalyze and accelerate the HER behavior, with electrocatalytic activity order being CP‐1/GCE > CP‐2/GCE > bare/GCE. The higher HER activity of the CP‐1/GCE can be attributed to that the coordination deformability of cuprous ion in CP 1 is greater. Furthermore, the recognition performance of CP‐1~2/GCE for glucose was further studied by chronoamperometry in 0.1 M NaOH. The two sensors can detect glucose in a linear range from 1 μM to 4 mM with sensitivities of 13.736 and 18.945 μA mM−1, and also revealed long‐term stability and good selectivity. These results indicate that cuprous CPs deserve further investigation as potential electrocatalyst candidates.

Directional Growth and Density Modulation of Single-Atom Platinum for Efficient Electrocatalytic Hydrogen Evolution.

Dispersion of single atoms (SAs) in the host is important for optimizing catalytic activity. Herein, we propose a novel strategy to tune oxygen vacancies in CeO2-X directionally anchoring the single atom platinum (PtSA), which is uniformly dispersed on the rGO. The catalyst's performance for the hydrogen evolution reaction (HER) can be enhanced by controlling different densities of CeO2-X in rGO. The PtSA performs best optimally densified and loaded on homogeneous and moderately densified CeO2-X/rGO (PtSA-M-CeO2-X/rGO). It exhibited higher activity in HER with an overpotential of 25 mV at 0.5 M H2SO4 and 33 mV at 1 KOH than that of almost reported electrocatalysts. Furthermore, it exhibited stability for 90 hours at -100 mA cm-2 in 1 KOH and -150 mA cm-2 in 0.5 M H2SO4 conditions, respectively. Through comprehensive experiments and theoretical calculations, the suitable dispersion density of PtSA on the defects of CeO2-X with more active sites gives the potential for practical applications. This research paves the way for developing single-atom catalysts with exceptional catalytic activity and stability, holding promise in advanced green energy conversion through defects engineering.

Binder-free nickel/boron-doped diamond film electrodes for hydrogen evolution reaction in alkaline medium: Effect of nickel catalyst nanostructure on electrochemical performance

Boron-doped diamond (BDD) is a robust electrode material, and Ni metal is a promising alternative electrocatalyst to noble metals for promoting the hydrogen evolution reaction. In this study, binder-free Ni/BDD film electrodes, with Ni acting as a catalyst, were constructed. With thermal annealing temperature regulation, the Ni catalyst exhibited different nanostructures, including amorphous continuous films, partially crystalline corrugated films, and uniformly dispersive nanoparticles. The electrodes were characterized via scanning electron microscopy, grazing-incidence X-ray diffraction, and X-ray photoelectron spectroscopy. Furthermore, the impact of the Ni catalyst fine structure on the hydrogen evolution reaction performance was evaluated. The results highlighted the versatility of BDD as a platform for developing binder-free Ni/BDD electrodes. Through precise adjustment of the nano-scale structure of Ni catalysts on the BDD surface, high hydrogen evolution reaction activity was achieved, with an overpotential as low as 273 mV at 10 mA/cm2 in a 1 M KOH solution.

Strong Metal-Support Interaction Modulation between Pt Nanoclusters and Mn3O4 Nanosheets through Oxygen Vacancy Control to Achieve High Activities for Acidic Hydrogen Evolution.

The optimization of metal-support interactions is used to fabricate noble metal-based nanoclusters with high activity for hydrogen evolution reaction (HER) in acid media. Specifically, the oxygen-defective Mn3O4 nanosheets supported Pt nanoclusters of ≈1.71nm in diameter (Pt/V·-Mn3O4 NSs) are synthesized through the controlled solvothermal reaction. The Pt/V·-Mn3O4 NSs show a superior activity and excellent stability for the HER in the acidic media. They only require an overpotential of 19mV to drive -10mAcm-2 and show negligible activity loss at -10 and -250mAcm-2 for >200 and >60h, respectively. Their Pt mass activity is 12.4 times higher than that of the Pt/C and even higher than those of many single-atom based Pt catalysts. DFT calculations show that their high HER activity arises mainly from the strong metal-support interaction between Pt and Mn3O4. It can facilitate the charge transfer from Mn3O4 to Pt, optimizing the H adsorption on the catalyst surface and promoting the evolution of H2 through the Volmer-Tafel mechanism. The oxygen vacancies in the V·-Mn3O4 NSs are found to be inconducive to the high activity of the Pt/V·-Mn3O4 NSs, highlighting the great importance to reduce the vacancy levels in V·-Mn3O4 NSs.

Origin of the synergistic effects of bimetallic nanoparticles coupled with a metal oxide heterostructure for accelerating catalytic performance

AbstractPrecisely tuning bicomponent intimacy during reactions by traditional methods remains a formidable challenge in the fabrication of highly active and stable catalysts because of the difficulty in constructing well‐defined catalytic systems and the occurrence of agglomeration during assembly. To overcome these limitations, a PtRuPNiO@TiOx catalyst on a Ti plate was prepared by ultrasound‐assisted low‐voltage plasma electrolysis. This method involves the oxidation of pure Ti metal and co‐reduction of strong metals at 3000°C, followed by sonochemical ultrasonication under ambient conditions in an aqueous solution. The intimacy of the bimetals in PtRuPNiO@TiOx is tuned, and the metal nanoparticles are uniformly distributed on the porous titania coating via strong metal‒support interactions by leveraging the instantaneous high‐energy input from the plasma discharge and ultrasonic irradiation. The intimacy of PtRuPNiO@TiOx increases the electron density on the Pt surface. Consequently, the paired sites exhibit a high hydrogen evolution reaction activity (an overpotential of 220 mV at a current density of 10 mA cm−2 and Tafel slope of 186 mV dec−1), excellent activity in the hydrogenation of 4‐nitrophenol with a robust stability for up to 20 cycles, and the ability to contrast stated catalysts without ultrasonication and plasma electrolysis. This study facilitates industrially important reactions through synergistic chemical interactions.

Cobalt phosphide embedded on interconnected ultrathin carbon nanosheets as an electrocatalyst for hydrogen evolution in alkaline medium

A highly effective hydrogen evolution reaction (HER) electrocatalyst was developed by combining Co2P nanoparticles (Co2P NPs) embedded on interconnected and ultrathin carbon nanosheets (CNS) through a facial in-situ thermal decomposition of the cobalt-triphenylphosphine complex. CNS were derived from the pyrolysis of sodium citrate in one step, resulting in an interconnected ultrathin nanosheet structure with a small thickness. The interaction between Co2P NPs and CNS boosted the electron transfer rate, resulting in a remarkable electrocatalytic performance toward the HER in an alkaline solution with excellent durability. An overpotential of −200 mV vs. RHE was sufficient to afford a current density of −10 mA cm−2 with a Tafel slope of 83.4 mV dec−1 in potassium hydroxide medium (1.0 M), which are lower than that of Co2P nanoparticles (-250 mV) with Tafel slope 93.3 mV dec−1. The electrochemical impedance spectroscopy data illustrated that the mutual coupling between the Co2P NPs and CNS supports the electrochemical HER performance and accelerates the kinetic of electron transfer. The high HER activity of the novel Co2P NPs/CNS catalyst is ascribed to the presence of CNS robust support.

Phase Engineering and Dispersion Stabilization of Cobalt toward Enhanced Hydrogen Evolution.

Phase engineering is promising to increase the intrinsic activity of the catalyst toward hydrogen evolution reaction (HER). However, the polymorphism interface is unstable due to the presence of metastable phases. Herein, phase engineering and dispersion stabilization are applied simultaneously to boost the HER activity of cobalt without sacrificing the stability. A fast and facile approach (plasma cathodic electro deposition) is developed to prepare cobalt film with a hetero-phase structure. The polymorphs of cobalt are realized through reduced stacking fault energy due to the doping of Mo, and the high temperature treatment resulted from the plasma discharge. Meanwhile, homogeneously dispersed oxide/carbide nanoparticles are produced from the reaction of plasma-induced oxygen/carbon atoms with electro-deposited metal. The existence of rich polymorphism interface and oxide/carbide help to facilitate H2 production by the tuning of electronic structure and the increase of active sites. Furthermore, oxide/carbide dispersoid effectively prevents the phase transition through a pinning effect on the grain boundary. As-prepared Co-hybrid/CoO_MoC exhibits both high HER activity and robust stability (44mV at 10mA cm-2, Tafel slope of 53.2mV dec-1, no degradation after 100 h test). The work reported here provides an alternate approach to the design of advanced HER catalysts for real application.

Electrodes composited by bisbenzimidazole silver(I) coordination polymers as electrocatalysts for hydrogen evolution and H2O2-sensing

Two new silver(Ⅰ) coordination polymers (CPs) {[Ag2(p-HMOPhIDC)(BBP)](H2O)}n (1), {[Ag2(m-HMOPhIDC)(BBP)](H2O)}n (2) (BBP = 1,3-[bis(2,2′-benzimidazole)] propane, p-H3MOPHIDC = 2-(4-methoxyphenyl)–2H-imidazole-4,5-dicarboxylic acid, m-H3MOPHIDC = 2-(3-methoxyphenyl)–2H-imidazole-4,5-dicarboxylic acid), were prepared under hydrothermal condition and structurally characterized. The CPs 1–2 both exhibit binuclear 1D “square waveform” chain structures. Structural analysis shows that the two silver ions in CP 1 are crystallographically independent but chemically identical; whereas the two silver ions in CP 2 are crystallographically independent and chemically different. Electrocatalytic hydrogen evolution reaction (HER) of carbon paste composite electrodes (CPCEs 1–2) prepared by mixing graphite powder with coordination polymers was investigated by variable temperature linear sweep voltammetry (VT-LSV), controlled potential electrolysis (CPE) and electrochemical impedance spectroscopy (EIS) in 0.5 M H2SO4 electrolyte. It was found that the overpotential η10293K of CPCEs 1–2 positively shifted 449 and 172 mV compared with sCPCE (−966 mV), and the Tafel slope of sCPCE and CPCE 1–2 were 276, 160 and 226 mV dec-1, respectively. The results proved that CPCEs 1–2 could effectively catalyze and accelerate the HER behavior. The higher HER activity of the CPCE 1 than CPCE 2 can be attributed to the fact that CP 1 contains more three-coordinated silver ions. Moreover, the recognition performance of CPCEs 1–2 for H2O2 was further studied by chronoamperometry in 0.2 M phosphate buffer solution (PBS, pH = 6). The two sensors can detect H2O2 in a linear range from 0.5 μM to 4 mM with a detection limit of 128 µM for CPCE 1 and 27.1 µM for CPCE 2 at a signal-to-noise ratio of 3, and also revealed long-term stability and good selectivity.

Hierarchical multiphase heterointerfaces Ni2P–CoP/MoO2 catalyst for efficient and stable hydrogen evolution reaction over the entire pH range

The development of pH-versatile, high-performing, and durable catalysts for hydrogen evolution reaction (HER) is crucial to satisfy the complex environment of water electrolysis industry. Herein, we present the synthesis of a hierarchical multiphase heterointerfaces Ni2P–CoP/MoO2 nanocatalyst with exceptionally high HER activity in the entire pH range through a facile three-step process involved hydrothermal, electrodeposition, and in situ phosphating treatment. Experiments and characterization revealed the strong electronic interactions among the phases of Ni2P, CoP, and MoO2, which endowed the Ni2P–CoP/MoO2 with high hydrogen evolution activity in different pH ranges. Meanwhile, the layered structure of our as-prepared catalyst makes the massive exposure of active sites. As a result, the Ni2P–CoP/MoO2 catalyst shows remarkable performance, requiring mere overpotentials of 33, 41, and 23 mV to drive 10 mA cm−2 in 1 M KOH, 1 M phosphate buffer solution, 0.5 M H2SO4, respectively. Moreover, the catalyst exhibits excellent stability in the chronopotentialmetry test under different pH electrolyte. Impressively, the Ni2P–CoP/MoO2 catalyst coupled with Ni–Fe LDH to form an overall water splitting system only require 1.50 V to drive 10 mA cm−2. Furthermore, this system actuated by wind and solar energy can stably undergo a continuous production of hydrogen and oxygen.