LAUSR

Monolithic integrated photoelectrochemical devices consisting of semiconductors and co-catalysts have always been restricted by the trade-off between light absorption and catalytic activity upon frontside illumination. Herein, we proposed a facile strategy to spatio-selectively deposit Pt catalyst on the top of p-Si micro-pyramids, which not only enables substantial light absorption but also immensely boosts the charge transport and mass transfer. With the help of dark-field microscopy and microscopic photocurrent mapping, it is revealed that the top of p-Si micro-pyramids is an ideal electron-migration channel for efficient charge carrier extraction. This spatio-selective strategy affords the Si photocathode to achieve a high applied bias photon-to-current efficiency of 3.84% for hydrogen production, significantly greater than the control sample with the same amount of Pt catalyst deposited uniformly on the same substrates (0.04%).