Gd-doped CuBi_(2)O_(4)/CuO heterojunction film photocathodes for photoelectrochemical H_(2)O_(2)production through oxygen reduction

Photoelectrochemical oxygen reduction reaction(ORR)toward H_(2)O_(2)is highly desirable because only sunlight,O_(2)and water are required in the process.However,the corresponding studies are still at its infancy because of the lack of suitable photocathodes,especially inorganic semiconductor photocathodes.In this work,we report CuBi_(2)O_(4)/CuO(CBO/CuO)heterojunction submicrocrystalline film photocathodes with efficient ORR activity for H_(2)O_(2)production.The heterojunction film photocathodes were prepared through thermal evaporation of Cu and Bi metals under vacuum and subsequent annealing treatment.Furthermore,the doping of Gd^(3+)ions into CBO/CuO could significantly enhance the yield of H_(2)O_(2).As a result,the concentration of H_(2)O_(2)could reach 1.3 mM within 30 min,which is 6 times higher than that obtained on the pristine CBO/CuO photocathode.The theoretical calculations suggested that the introduction of Gd could adjust the electronic structure of CBO surface and promote 2e ORR pathway for selective production of H_(2)O_(2).Our work not only provides a new strategy for designing highly efficient photocathode for H_(2)O_(2)production but also will evoke more interest in photoelectrocatalytic ORR through inorganic semiconductor photocathode.