Ni-doped Cu oxide catalysts for ORR: suppressing H2O2 formation by engineering chemical strain

Abstract

Ni-doped copper oxide (Cu[Ni]Ox/Au) has demonstrated considerable promise towards efficient oxygen reduction reaction (ORR) under alkaline conditions. The Cu-rich samples like Cu0.8Ni0.2Ox/Au show better activity and selectivity than benchmarks such as Pt and Au, exhibiting H2O2 yields < 5% throughout a large potential range. The electrode's performance did not degrade even under 3000 potential cycles under ORR conditions. In-situ Raman spectroscopy indicated a Cu-O-Ni type framework where Ni doping into CuOx results in coordinatively unsaturated Ni centers within the Cu-O-Ni framework. These centers are active towards easier cleavage of O-O bonds resulting in an overall preference for the 4e pathway for O2 reduction to H2O.