The combination of biomass platform molecular oxidation with water electrolysis represents a promising strategy for low-energy hydrogen production and concurrent high-value chemicals generation. However, the practical implementation of this approach is still hindered by high overpotentials, inadequate selectivity, limited catalyst multifunctionality, and poor long-term stability. Herein, we developed a graphitized carbon-modified nickel nitride/nickel gradient heterostructure (C@Ni-N/Ni) synthesized through a facile strategy involving adsorption and subsequent high-temperature calcination. Experimental and theoretical results reveal that the constructed multi-interfacial structures (Ni3N/Ni, Ni3N/C, and Ni/C) with a gradient Ni distribution effectively optimize intermediate adsorption energies and facilitate the transition of low-valence nickel species (Ni0, Ni2+) to a higher valence state (Ni3+), thereby significantly accelerating the reaction kinetics of ethanol oxidation to acetate. Consequently, the integrated electrolysis system demonstrates remarkable performance, requiring only 1.44 V of cell voltage (without iR compensation) to achieve a current density of 10 mA·cm−2, while simultaneously delivering a high Faradaic efficiency of 91% for acetate production and exhibiting excellent stability. Furthermore, C@Ni-N/Ni gradient heterostructure also displays promising catalytic activity toward the electrooxidation of other small molecules, demonstrating its versatility. This study highlights a multi-interface coupled gradient engineering strategy for precise regulation of active sites, offering valuable insights for efficient biomass valorization and energy-saving hydrogen production.

Oxygen evolution reaction (OER), limited by high overpotential and sluggish kinetics, represents a major bottleneck for electrochemical water splitting toward green hydrogen production. Constructing asymmetric A–O–B motifs to modulate the electronic density of states near the Fermi level through orbital coupling is crucial for optimizing the surface chemisorption properties of transition metals, thereby enabling the development of electrocatalysts with high intrinsic activity and stability. Herein, an IrOx nanocluster-coupled Fe/Eu co-doped nickel telluride composite catalyst (IrOx/FeEu-NiTex) with ultralow Eu (0.72 at%) and Ir (0.14 at%) content was synthesized using an in situ hydrothermal method followed by an electrochemical deposition strategy. Benefiting from the design of an asymmetric dual-electron bridge structure with gradient orbital coupling (Ni 3d–O 2p–Eu 4f, Ni 3d–O 2p–Ir 5d), the electronic structure of the catalyst is effectively modulated, thereby enabling the optimization of adsorption behaviors for reaction intermediates. Consequently, the optimized IrOx/FeEu-NiTex electrode exhibits superior OER performance, delivering low overpotentials of 205 mV and 334 mV at current densities of 10 mA cm−2 and 500 mA cm−2, respectively. Furthermore, it maintains long-term stability for over 1000 hours at high current densities of 500 and 1000 mA cm−2. When integrated into an alkaline water electrolyzer, the system achieves a current density of 500 mA cm−2 at a cell voltage of 1.64 V and demonstrates stable operation for over 1000 hours. This study successfully develops a high-performance rare-earth-based OER catalyst by constructing an asymmetric dual-electron bridge structure with gradient orbital coupling, providing new insights into electronic structure engineering strategies.

Electrolytic hydrogen production assisted by the sulfion oxidation reaction (SOR) offers a low-cost, energy-efficient alternative to conventional methods by replacing the anodic oxygen evolution reaction (OER), which reduces the required anode potential. However, scaling this technology requires bifunctional electrocatalysts that efficiently drive SOR and sustain the hydrogen evolution reaction (HER) at high current density in concentrated sulfion electrolytes. Herein, using a coordinated regulation strategy of interface and ligand, we constructed a nickel cobalt sulfide/ligand-functionalized nickel cobalt hydroxide composite catalyst (NiCo-S/NiCo-OH-CL) with rich sulfide/hydroxide heterointerfaces via a hydrothermal ion exchange method, using a metal-organic framework as the precursor. Benefiting from the porous network, sulfur-repellent hydrophilic surface, and dual electronic structure regulation from heterointerfaces and ligands, it demonstrates excellent SOR and HER activity. The constructed coupled electrocatalytic system requires an ultra-low cell voltage of only 0.62 V at a current density of 100 mA cm−2, achieving a cathodic hydrogen Faraday efficiency of ≥95% and operational stability for over 3200 hours or 133 days. The sulfur and hydrogen yields reach 0.36 kg h−1 m−2 and 0.036 kg h−1 m−2, respectively. This work advances a synergistic interface-ligand modulation strategy for bifunctional catalysts and demonstrates a pathway for energy-efficient hydrogen production and sulfur recovery.