Etching reconstruction of ultrathin layered NiFe-hydroxide: building synergistic V _Fe(III) /Ni( iii ) active structures for an efficient urea oxidat

High-density cation vacancies rearrange Ni electrons, converting more Ni ²⁺ into key active Ni ³⁺ species, while promoting ultrathin structures that enlarge specific surface area and expose more active sites.