Advanced Catalytic Materials for Efficient Electrochemical Hydrogen and Oxygen Evolution Reactions in Sustainable Energy Conversion

Electrochemical water splitting enables renewable hydrogen production, yet laboratory catalyst activity often fails to translate into durable electrolyzer performance. This review integrates interfacial mechanisms, performance evaluation, degradation, and device requirements within a unified framework for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Noble-metal and non-noble-metal catalysts are compared using common criteria encompassing intrinsic activity, conductivity, stability, reconstruction, and resource use. Electronic-structure regulation, defect engineering, heterointerfaces, phase control, and strain are evaluated as interconnected design strategies. Magnetic-field effects are examined by distinguishing spin-dependent kinetics from transport and bubble removal. Density functional theory (DFT) links descriptors and kinetic barriers to electrochemical environments and operando identification of active structures. Translation to proton-exchange-membrane (PEM), alkaline, and anion-exchange-membrane (AEM) electrolyzers highlights catalyst-layer design, realistic current densities, and dynamic operation. This framework guides joint optimization of activity, durability, working-state structure, material utilization, and device-level transport.