Synergetic modulation of the electronic structure and hydrophilicity of nickel–iron hydroxide for efficient oxygen evolution by UV/ozone treatment

In this work, a new surface engineering technique through UV/ozone treatment to improve the oxygen evolution reaction performance of nickel-iron hydroxide based catalysts has been developed. It is found that UV/ozone treatment can significantly improve the hydrophilicity of the catalysts as well as modify the electronic structure at the Ni–Fe center and oxidize Ni2+ to Ni3+, which consequently enables better electrode–electrolyte contacts, stronger charge-transfer and more numbers of active sites with higher intrinsic activity during the OER. This work demonstrates UV/ozone treatment as a highly effective strategy towards the rational design of high-performance electrocatalysts by exploiting surface modifications.