Serpentine CoxNi3-xGe2O5(OH)4 nanosheets with tuned electronic energy bands for highly efficient oxygen evolution reaction in alkaline and neutral electrolytes

It is widely accepted that electronic energy bands of materials seriously affect electrocatalytic performance. However, for transition metal based serpentine materials, the influence of transition metal elements, Ge, and Si on energy bands and subsequently the electrocatalytic OER behavior is not concern yet. Herein, serpentine CoxNi3-xGe2O5(OH)(4) nanosheets with tuned energy bands are designed for catalyzing OER. DFT calculations reveal that CoxNi3-xGe2O5(OH)(4) produce intensified density of states around Fermi level in energy bands, bringing feasible absorption of OER intermediates. In experiment, optimized CoxNi3-xGe2O5(OH)(4) shows low OER overpotential and favorable stability in KOH solution and phosphatic buffer saline, which is superior to commercial RuO2 and most Co and Ni based compounds. Electrochemical impedance spectra reveal that CoxNi3-xGe2O5(OH)(4) possesses minimized adsorptive resistance of surface intermediates, which consistent with results of DFT calculations. The serpentine catalysts with tuned energy bands are promising as efficient electrocatalysts for water splitting in wide-pH environments.