Sub-3 nm pores in two-dimensional nanomesh promoting the generation of electroactive phase for robust water oxidation

Herein, abundant and uniform nanopores with sub-3-nm sizes are introduced to 1.5 nm-thick nickel-iron layered double hydroxide (NiFe LDH) ultrathin nanosheets via an etching-aging process, realizing remarkable enhancement in oxygen evolution reaction (OER) performance. Detailed analyses revealed that the NiFe LDH phase around the nanopores can be preferentially oxidized into electroactive Fe:NiOOH phase. In addition, the buffering space provided by the nanopores can effectively avoid structural deformation during repeated redox cycling, leading to better electrochemical stability, which synergistically make the catalyst a promising candidate for commercial water splitting. This work highlights the positive role of porous structure in accelerating the formation of active phases beyond just increment of surface area, which can provide insight in designing advanced catalysts.