Fig. 4

The photocatalytic overall water-splitting activity tests in the light furnace. a A photographic image of a four-mirror floating-zone light furnace from Crystal Systems Inc. (Supplementary Fig. 18) used to mimic a solar concentrator to focus a light beam to provide both heat and photons to the N-doped TiO₂ without any other energy input from an electrical device. b The reactor temperature of 270 °C is maintained by this light source, and H₂ evolution rates of about 12 and 20 mmol g⁻¹ h⁻¹ were achieved over Au- promoted N-P25-620 and N-P25-620/MgO(111), respectively. Error bars indicate the standard deviation