Synergistic activation of bimetallic sulfides via hierarchical architecture: a superior bifunctional electrocatalyst for efficient hydrogen evolution and iodine reduction.

Currently, the most efficient electrocatalyst for the hydrogen evolution reaction (HER) in water dissociation is Pt‐based catalyst. Unfortunately, the high cost and less than perfect efficiency hinder wide‐range industrial/technological applications. Here, by controlling the treatment temperature of tris (2,2‐bipyridine) ruthenium dichloride hexahydrate, synthesis of compounds with novel ruthenium single/dual atoms (Ru S/DAs) mixed with Ru nanoclusters (Ru S/DAs + Ru NCs) and supported by carbon dots is demonstrated. These compounds are shown to be highly efficient and competitive catalysts for hydrogen evolution. Ru S/DAs + Ru NCs exhibit very high activity, with overpotentials of 15 and 40 mV at a current density of 10 mA/cm2 in 1.0 mol/L KOH and 0.5 mol/L H2SO4, respectively. Furthermore, the composites are found to possess outstanding stability and rapid HER kinetics. X ray absorption fine structure analysis, supported by density functional theory calculations, shows charge rearrangement in single‐atomic Ru, and the Ru dual sites promote active hydrogen adsorption and recombination. Ru S/DAs and Ru NCs demonstrate high electroactivity due to the electroactive Ru 4d orbitals. The introduction of Ru NCs activates the carbon support, providing a high electronic conductivity to transfer electrons from Ru NCs to Ru S/DAs, and facilitates water dissociation for the HER process.

Phase-controlled synthesis of polymorphic tungsten diphosphide with hybridization of monoclinic and orthorhombic phases as a novel electrocatalyst for efficient hydrogen evolution

Large‐scale development of low‐cost, efficient, and stable powder electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solutions is a key step toward commercial hydrogen production. Herein, a hierarchical NiMo‐MoO3-x hollow nanotube (NiMo‐MoO3-x‐HNT) with bifunctional groups as an efficient HER electrocatalyst was strategically invented using an MoO3 nanorod (MoO3−NR) as the precursor. The synthesis mechanism of the NiMo‐MoO3-x‐HNT is established based on in‐depth investigations using diffraction, spectral, and microscopy results. Experimental results suggest that the NiMo‐MoO3-x‐HNT exhibits excellent electrocatalytic HER performance in 1 M KOH, with a low overpotential of 26.5 mV@10.0 mA cm-2 and a small Tafel slope of 32.6 mV dec–1. These values are comparable to those of cutting‐edge electrocatalysts based on platinum‐group metals. Moreover, it exhibits an almost unaffected cyclic stability over 50,000 cycles and robust durability over 98 h. This remarkable performance is attributed to its bifunctional groups and the porous hierarchical hollow nanotubular morphology. In summary, this study proposes a novel, efficient, and cost‐effective strategy for the development of noble metal‐free, high‐performance HER electrocatalysts.

The development of advanced electrocatalysts plays a pivotal role in enhancing hydrogen production through water electrolysis. In this study, we employed a two-step electrodeposition method to fabricate a 3D porous Cu-Co-Ni alloy with superior catalytic properties and long-term stability for hydrogen evolution reaction (HER). The resulting trimetallic alloy, Cu@Cu-Ni-Co, demonstrated significant improvements in structural integrity and catalytic performance. A comparative analysis of electrocatalysts, including Cu, Cu@Ni-Co, and Cu@Cu-Ni-Co, revealed that Cu@Cu-Ni-Co achieved the best results in alkaline media. Electrochemical tests conducted in 1.0 M NaOH showed that Cu@Cu-Ni-Co reached a current density of 10 mA cm−2 at a low overpotential of 125 mV, along with a low Tafel slope of 79.1 mV dec−1. The catalyst showed exceptional durability, retaining ~95% of its initial current density after 120 h of continuous operation at high current densities. Structural analysis confirmed that the enhanced catalytic performance arises from the synergistic interaction between Cu, Ni, and Co within the well-integrated trimetallic framework. This integration results in a large electrochemical active surface area (ECSA) of 380 cm2 and a low charge transfer resistance (15.76 Ω), facilitating efficient electron transfer and promoting superior HER activity. These findings position Cu@Cu-Ni-Co as a highly efficient and stable electrocatalyst for alkaline HER in alkaline conditions.

Fe/Ni bi-metallic organic framework supported 1T/2H MoS2 heterostructures as efficient bifunctional electrocatalysts for hydrogen and oxygen evolution

Insights into the combined effect of coupled CuFeO2/Fe3O4 heterostructured hybrid electrocatalyst for efficient hydrogen evolution in water splitting

Developing cost-effective and earth-abundant noble-metal-free electrocatalysts is imperative for the imminent electrochemical society. Two-dimensional Ti3C2TX (MXene) exhibits tunable properties with high electrical conductivity and a large specific surface area, which improve its electrochemical performance. Herein, the low-temperature annealing method is used to enrich MXene with a maximum number of Ti-O terminals without formation of titanium dioxide (TiO2) under neutral pH conditions. MXene annealed at 200 °C is found to have a large number of Ti-O termination groups, resulting in a large electrochemically active surface area and increased active sites (-O termination groups) and hence excellent electrocatalytic performance compared to other samples as well as previous reported work. The optimized sample is found to show the lowest overpotential value of 0.07 V at 10 mA cm-2 and a Tafel slope of 0.15 V dec-1 toward the hydrogen evolution reaction (HER), whereas for the methanol oxidation reaction (MOR), the current density is 18.08 mA cm-2, and the onset potential is -0.51 V. In addition, it also shows long-term stability and durability toward HER as well as MOR.

Synthesis of polyoxometalates derived bifunctional catalyst towards efficient overall water splitting in neutral and alkaline medium

The sluggish reaction kinetics and insufficient active sites remain key challenges for transition metal carbide catalysts in the hydrogen evolution reaction under alkaline conditions. In this work, we successfully construct a Mo2C/MoO2 heterojunction on a nitrogen-doped carbon substrate, effectively regulating the electronic structure and surface properties. Moreover, the efficient interfacial electron transfer optimizes hydrogen adsorption energy, thus facilitating reaction kinetics and improving the catalytic activity. In alkaline and alkaline saltwater environments, this catalyst exhibits hydrogen evolution activity comparable to commercial Pt/C (overpotential of only 13/23 mV at 10 mA cm-2) and stability lasting up to 300 hours. This work provides new insights into designing high-performance non-precious metal electrocatalysts through interfacial engineering, holding significant implications for advancing the industrialization of water electrolysis hydrogen production technology.

Metal organic framework derived Ni0.15Co0.85S2@MoS2 heterostructure as an efficient and stable electrocatalyst for hydrogen evolution

Fe doped skutterudite-type CoP3 nanoneedles as efficient electrocatalysts for hydrogen and oxygen evolution in alkaline media

We developed highly efficient electrocatalysts for hydrogen evolution through the noncovalent integration (via electrostatic and π ‐ π interactions) of tetra‐hydroxythioethyl‐substituted metal‐free (H 2 Pc) and cobalt(II) phthalocyanines (CoPc) with boron‐doped carbon quantum dots (CBQdot). Incorporation of CBQdots greatly enhanced the molecular organization and uniformity of H 2 Pc and CoPc through strong interfacial interactions. π – π stacking, hydrogen bonding, and coordination between cobalt center and CBQdot surface groups led to well‐ordered nanoconjugate systems. Raman analyses showed a decreased D / G ratio, particularly in CoPc/CBQdot, indicating defect passivation and improved interfacial ordering. SEM, EDX, and AFM results demonstrated reduced aggregation, smaller uniformly dispersed particles, and smoother, more continuous film morphologies. The hybrid CoPc/CBQD catalyst demonstrated exceptional HER activity in acidic media, significantly outperforming the CBQDots, H 2 Pc, and CoPc. Remarkably, the hybrid catalyst demonstrated superior hydrogen evolution reaction (HER) activity in acidic media, achieving a low overpotential of 434 mV at 10 mA cm −2 current density with a favorable Tafel slope of 124 mV dec −1 . This enhanced performance originates from the synergistic π ‐ π stacking interactions between the phthalocyanine core and the carbon quantum dots, which effectively modulates the catalyst's active surface area. Our findings present a technologically viable approach for developing noble‐metal‐free HER catalysts. The strategic design of these π ‐ π stacked nanoconjugates offers a promising pathway for efficient hydrogen production, addressing both performance and cost considerations in renewable energy applications.

In situ formation of Co/N-carbon via pyrolysis of layered cobalt metal–organic frameworks in argon atmosphere was performed. As excellent hydrogen evolution reaction (HER) catalysts, the 2D hybrid layered structure composed of metallic cobalt and N-carbon exhibited a small overpotential of 103 mV (vs RHE) at 10 mA/cm2, high cycle durability and considerable long-term stability for HER. The superior electrochemical performance of Co/N-carbon for HER could be attributed to such 2D setup that encompasses the low H atom binding energy of metallic cobalt, the high conductivity of carbon and the stability of carbon-encapsulated Co nanoparticles.

To facilely develop low-cost and efficient hydrogen evolution electrocatalysts, catalyst with low content of platinum on nitrogen-doped carbon nanoporous structures were prepared for hydrogen evolution reaction (HER). This study firstly demonstrated the one-step pyrolysis transformation of conveniently accessible mulberry leaves to obtain nitrogen-doped nanoporous carbons (N-NPCs) for hydrogen evolution reaction. After electrochemical treatment, the obtained N-NPCs-ET with Pt as counter electrode exhibited an unexpected high hydrogen evolution activity, which had low onset overpotential of 100 mV and a Tafel slope of 60 mV dec-1. N-NPCs-ET maintained catalytic activity for at least 10 h in 0.5 M H2SO4 solution. The enhanced HER performance was relevant to the incorporation of Pt nanoparticles, which were dissolved from anodic Pt counter electrode in acid media and precipitated into cathodic N-NPCs surface again. Moreover, for the first time, we found that with a gold electrode as the counter electrode, Au nanoparticles could be incorporated into N-NPCs by electrochemical treatments and the formed Au nanoparticles decorated N-NPCs possessed efficient catalytic activity toward HER.

The exploition of cost-efficient and high-performance catalysts to boost hydrogen generation in overall water splitting is crucial to economically obtain green hydrogen energy. Herein, we propose a novel electrocatalyst consisting of spherical RuS2 on S-doped reduced graphene oxide (s-RuS2/S-rGO) with high catalytic behavior toward hydrogen evolution reaction (HER) in all pH conditions, especially in alkaline electrolytes. RuS2/S-rGO delivers small overpotentials of 25 and 56 mV at current densities of 10 and 50 mA cm-2, respectively, and a low Tafel slope of 29 mV dec-1 with good stability for 100 h in basic solutions. This performance is comparable to and even exceeds that of documented representative electrocatalysts, including the benchmark Pt/C; since the price of Ru is about 1/25th that of Pt, this novel electrocatalyst offers a low-cost alternative to Pt-based HER electrocatalysts. Ruthenium-centered sites of RuS2 in this hybrid catalyst are responsible for the HER active sites, and S doping in RuS2 also exerts an important function for the HER activity; density functional theory calculations disclose that the water dissociation ability and adsorption free energy of hydrogen intermediate adsorption (Δ GH*) for RuS2 are very close to those of Pt. A homemade electrolyzer with an s-RuS2/S-rGO (cathode)//RuO2/C (anode) couple presents a relatively low voltage of 1.54 V at a current density of 20 mA cm-2, while maintaining negligible deactivation over a 24 h operation.