LAUSR

Abstract Although it is known that the efficacy of photoelectrocatalysts is enhanced by increasing the amount of high energy surface exposed, the development of a universal synthesis method with both superior activity and simplicity is needed for scalable applications. We herein controllably fabricated cuprous oxide (Cu 2 O) micro crystals with different morphologies, evolving from cubes, cuboctahedra, truncated octahedra and finally to octahedra on indium tin oxide (ITO) glass substrates, by a facile electrochemical deposition method. The structures of facet-engineered Cu 2 O samples and the underlying mechanism for the morphology evolution were investigated. The separation of photogenerated hole-electron pairs on Cu 2 O crystals with different exposed facets was characterized by measuring the photocurrent densities with chopped illumination, which increased with the increased concentrations of PVP: the octahedral Cu 2 O crystals, with the highest proportion of {111} facets exposed, exhibited the lowest electro-hole recombination in contrast to the cubes, cuboctahedra, and truncated octahedra, respectively. The photoelectrocatalytic degradation efficiency of the o-chlorophenol (2-CP) pollutant under sunlight irradiation with Cu 2 O-coated photocathode was further investigated to reveal the effect of different exposed facets. Due to the increased number of surface active sites available for degradation reactions, the octahedral Cu 2 O microcrystals presented higher photoelectrocatalytic activity compared to other shapes. Active oxygen species detected by electron spin-resonance (ESR) spectrometry implied that abundant superoxide radicals (O 2 ●− ) were the dominant active radicals in the degradation.