Recent progress in non-noble metal nano-electrocatalysts for hybrid water splitting

Hybrid water splitting, which combines thermodynamically favorable inorganic/organic oxidation with hydrogen evolution, typically requires lower cell voltage to achieve the same current density as traditional water splitting. By replacing the sluggish oxygen evolution reaction (OER), the overall energy input required in hybrid water splitting can be greatly decreased. Moreover, by selecting the appropriate anodic substrate, energy-saving hydrogen production can be achieved alongside pollutant degradation or organic upgrading, thereby enhancing its practicality and environmental benefits. Recent advancements in nanostructured non-noble metal catalysts have shown significant potential for enhancing the anodic oxidation reaction performance. These nanocatalysts offer a platform for optimizing the reaction kinetics and selectivity owing to their high surface area and tunable properties, potentially eliminating the need for noble metal catalysts in hybrid water splitting. This review summarizes recent advances in non-noble metal nanocatalysts for diverse alternative anodic oxidation reactions, including pollutants' oxidative degradation and selective organic upgrading. Their performance, mechanism, and practical applications in hybrid water splitting are also highlighted. This review also discusses current challenges and future directions, such as targeted catalyst design, industrial-scale evaluation, electrolyte system optimization, and production collection-related problems. By addressing these issues, hybrid water splitting holds the promise of becoming a transformative technique for sustainable hydrogen production, offering both economic and environmental advantages.