Metal-vacancy-rich layered double hydroxides for ampere-level acidic water oxidation

Ru-vacancy-rich NiRu v -LDH is constructed on biomass-derived porous wood scaffolds. • Vacancy engineering enables electronic modulation and enhanced mass transport • The PEM electrolyzer operates at 1.75 V and 1 A cm −2 for over 2000 h • Ni-doped RuO 2 reconstruction and DFT reveal the activity-stability origin. Proton exchange membrane (PEM) water electrolysis is vital for green hydrogen production, but its acidic oxygen evolution reaction (OER) is hindered by sluggish kinetics and catalyst delamination. To address this, a self-supported electrode was fabricated by anchoring Ru-deficient layered double hydroxides on a natural camphorwood substrate (NiRu v -LDH). Camphorwood's 3D hierarchical porous architecture provides structural integrity and hydrophilic microchannels that accelerate mass transport and gas release, eliminating polymeric binders. A chemical etching strategy successfully introduced atomic-scale Ru vacancies, reconfiguring the local electronic structure, and lowering the OER overpotential to 215 mV at 10 mA cm −2 . In a PEM electrolyzer, the catalyst required only 1.75 V at 1.0 A cm −2 and demonstrated over 2000 h of industrial-grade stability. Crucially, during the PEM water splitting process, the NiRu v -LDH catalyst undergoes in-situ anodic oxidation to transform into Ni-RuO 2 , which exhibits exceptional stability in the acidic operating environment. Techno-economic analysis confirms its exceptional commercial viability, achieving a hydrogen production cost of ~US$ 1.1 per kg.