Journal Article 05175J654G CO2 reduction Coloring Agents Ir nanostructure Niobium Oxides Pt-Ni Research Support, Non-U.S. Gov't Solutions active sites asymmetrical electronic distribution atomic metal species carbon-based catalysts catalysts charge redistribution cycle life electrocatalysis electrocatalysts gradient materials intrinsic carbon defects lithium-CO2 batteries nitrogen vacancy overpotentials oxygen evolution oxygen reduction reaction selenium vacancies surface defects synergetic interaction urea oxidation reaction