Facet-dependent carrier dynamics of cuprous oxide regulating the photocatalytic hydrogen generation

Abstract

The intrinsic carrier dynamics of cuprous oxide (Cu2O) are known to have a crucial influence on photocatalytic performances. The photoactivity of rhombic dodecahedral Cu2O with dominant {110} facets (RD-Cu2O) is demonstrated to surpass that of cubic Cu2O with {100} surfaces (CB-Cu2O). Time resolved microwave conductivity (TRMC) measurements reveal the higher carrier mobility of RD-Cu2O when compared to CB-Cu2O. Additionally, modulated surface photovoltage (SPV) measurements further supported the better charge separation efficiency of RD-Cu2O. Although CB-Cu2O exhibited more pronounce SPV signals, the homogeneous distribution of electrical fields drives the majority charge inward and led to detrimental charge recombination. In contrast, the weak SPV signals for RD-Cu2O were attributed to a modulated distribution of charges towards the facets and facet boundaries, demonstrating a better charge separation. This study shows that carrier dynamics and defect density should also be regarded as facet-dependent properties that can have deciding influence on the photocatalytic activity. This journal is