Hierarchically Engineered NiSe ₂ ‐CuFeO ₂ Heterostructures on Biomass‐Derived Carbonized Wood for Efficient Ethanol‐Assisted Water Electrolysis

Rational design strategies for developing advanced electrocatalysts that replace the kinetically sluggish oxygen evolution reaction with the more thermodynamically favorable ethanol oxidation offer an effective pathway toward energy‐efficient hydrogen production. Herein, we strategically integrate NiSe 2 (NS) and CuFeO 2 (CFO) microstructures over biomass‐derived nitrogen‐doped carbonized wood (NCW) to construct a 3D, binder‐free, and bifunctional NS‐CFO@NCW electrode with a hierarchically interconnected heterostructure. The fusion of CFO cubes into the rough NS spheres establishes a strong interfacial interaction between the two components, which not only amplifies beneficial structural modulations but also tailors the electronic framework of Ni to equip the catalytically dynamic high‐valence phase. Benefiting from synergistic architecture, NS‐CFO@NCW exhibits superior ethanol oxidation reaction performance, delivering enhanced current density and favorable kinetics compared to its counterparts. When assembled into a bifunctional ethanol electrolyzer, the optimized NS‐CFO@NCW achieves an elevated current density of 100 mA cm −2 at a cell voltage of 1.63 V, representing a 190 mV reduction compared with that of standard water splitting, highlighting its remarkable energy efficiency. This work provides a sustainable design paradigm for coupling biomass upgrading with efficient hydrogen generation through advanced catalyst design and engineering.