Thermally Accelerated Surface Polaron Hopping in Photoelectrochemical Water Splitting

Electron-hole separation is a main challenge that limits the energy efficiency of photoelectrochemical water splitting for hydrogen fuel production. Surface polaron states with an energy level distribution near the conduction band are highly efficient charge separation passageways to massively accept or transfer the photogenerated electrons. Here, we found that the charge separation via surface polaron states could be further enhanced by heating (<100 degrees C) to accelerate the electron mobility of surface polaron states. As a result of heating from 30 to 70 degrees C, the saturated photocurrent increased about 34.5% under 1 sun and 18.3% under 10 suns from heat-induced increase in electron flux of surface polaron states. The heat-sensitive surface-state electron transfer provides a new heat-photoelectricity coupling mechanism to guide the design of new photoanodes that are available for complementary multienergy systems with high energy efficiency.

Automated summary

Electron-hole separation is a major challenge in photoelectrochemical water splitting for hydrogen fuel production. Surface polaron states near the conduction band can efficiently separate and transfer photogenerated electrons. We discovered that heating (<100 degrees C) can enhance charge separation via surface polaron states by increasing electron mobility. The saturated photocurrent increased by approximately 34.5% under 1 sun and 18.3% under 10 suns due to the heat-induced increase in electron flux of surface polaron states. This heat-sensitive surface-state electron transfer provides a new mechanism for heat-photoelectricity coupling and guides the design of efficient photoanodes for complementary multienergy systems.