Advances in catalytic hydrogen evolution

High-entropy alloy catalysts are an emerging class of materials and identification of catalytically active sites is critical. Here, we provide evidence that metal site electronegativity differences stabilize bound *OH and *H intermediates.

Microenvironment engineering through electrolyte optimization is a promising approach to mitigate catalyst poisoning effects in electrochemical systems, but the role of electrolyte anions is not fully understood. Here, in a combined experimental-theoretical evaluation, the authors study the effects of different acidic electrolytes (pH 1) on platinum for hydrogen (HER/HOR) and oxygen electrocatalysis (ORR/OER), finding that oxygen reduction performance can be improved 4-fold using nitric rather than sulfuric acid.

Van der Waals heterostructures stack together 2D materials to achieve unique performance. Here, 3D/3D heterostructures are created by inkjet printing of 2D MoS₂ and reduced graphene oxide, and demonstrated for a heterostructure catalyst for the hydrogen evolution reaction.

An alternative approach to defect-trapped Pt single-sites on a semiconductor is reported. Here, protruding Pt sites inhibit charge recombination and cause a tip effect which enhances H₂ evolution yield rates with minimal co-catalyst loading.

Efficient electron-hole separation and carrier utilization are key factors in photosynthetic systems. Here, the authors achieve efficient charge separation following a photogenerated hole-transfer band-trap pathway in the ternary composite Pt@NH₂-UiO-66/CdS, resulting in photocatalytic hydrogen evolution with good stability and a quantum efficiency of 40.3% at 400 nm irradiation.

The chemical pathways by which photocatalytic hydrogen production occurs remain to be fully understood. Here, a model system is studied, composed of single atoms deposited on quantum dots, attached to a primary photocatalyst.

Coupling the photo-oxidation of biomass-derived substrates with water splitting in a photoelectrochemical cell enables efficient hydrogen generation at the cathode. Here, a photoelectrochemical device employing a nanostructured WO₃ photoanode displays photocurrents of 6.5 mA cm⁻² through oxidation of glucose, in turn producing valuable products in the form of gluconic and glucaric acids, erythrose and arabinose.

Integrating green hydrogen production with the generation of valuable chemicals has the potential to increase the competitiveness of the system. Here, the authors quantitatively evaluate the energetic benefit of coupling hydrogen production with the hydrogenation of feedstocks in a photoelectrochemical device.

Renewable energy sources could be used to drive alkaline electrolyzers for large-scale hydrogen production. Here Yanghong Xia and colleagues show that the fluctuating nature of renewable energy sources compromises the efficiency and consistency of electrolyzer performance. They also show that a strategy of multi-mode self-optimization can address this problem, extending the range of operation as well as improving efficiency at low loads.