Highly Efficient Temperature-Induced Visible Light Photocatalytic Hydrogen Production from Water

Intensive effort has led to numerous breakthroughs for photoprocesses. So far, however, energy conversion efficiency for the visible-light photocatalytic splitting of water is still very low. In this paper, we demonstrate (1) surface-diffuse-reflected-light can be 2 orders of magnitude more efficient than incident light for photocatalysis, (2) the inefficiency of absorbed visible light for the photocatalytic H2 production from water with a sacrificial agent is due to its kinetic limitation, and (3) the dispersion of black Pt/TiO2 catalyst on the light-diffuse-reflection-surface of a SiO2 substrate provides a possibility for exploiting a temperature higher than H2O boiling point to overcome the kinetic limitation of visible light photocatalytic hydrogen production. Those findings create a novel temperature-induced visible light photocatalytic H2 production from water steam with a sacrificial agent, which exhibits a high photohydrogen yield of 497 mmol/h/gcat with a large apparent quantum efficiency (QE) of 65.7% for entire visible light range at 280 °C. The QE and yield are one and 2 orders of magnitude larger than most reported results, respectively.