High-Entropy Materials for Electrochemical Gas Conversion

High-entropy materials (HEMs) are composed of multiple principal elements stabilized by the configurational entropy. They establish a new design paradigm in electrocatalysis by leveraging local disorder and multielement synergy to create diverse and tunable active site environments. While HEMs have been broadly reviewed, a focused and reaction-specific assessment of their role in gas-involved electrocatalysis is absent. This review fills that gap by examining entropy-driven design principles, entropy-guided synthesis, nanoscale structural control, and advanced characterization of HEMs and by linking these aspects to their reaction-specific catalytic behavior in gas-involved electrocatalysis. We build a unified framework linking high-entropy chemistry to catalytic function across five key reactions: the CO2 reduction reaction (CO2RR), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), and nitrogen oxidation reaction (NOR). We provide comprehensive coverage across all major HEM families, including high-entropy alloys, oxides, chalcogenides, hydroxides, fluorides, MXenes, and single-atom configurations, highlighting features unique to each system. Key challenges and future directions are outlined, including scalable synthesis, active-site identification, machine-learning-guided discovery, and interfacial engineering. This review provides a reaction-focused framework for advancing HEM-based electrocatalysis and offers guidance for designing next-generation materials for clean energy technologies.