The photocatalytic wastewater hydrogen production process with superior performance to the overall water splitting

The utilization of a cost-free sacrificial agent is a novel approach to significantly enhance the efficiency of photocatalytic hydrogen (H₂) production by water splitting. Wastewater contains various organic pollutants, which have the potential to be used as hole sacrificial agents to promote H₂ production. Our studies on different pollutants reveals that not all pollutants can effectively promote H₂ production. However, when using the same pollutants, not all photocatalysts achieved a higher H₂ evolution rate than pure water. Only when the primary oxidizing active species of the photocatalyst are •OH radicals, which are generated by photogenerated holes, and when the pollutants are easily attacked and degraded by •OH radicals, can the production of H₂ be effectively promoted. It is noteworthy that the porous brookite TiO₂ photocatalyst exhibits a significantly higher H₂ evolution rate in Reactive Red X-3B and Congo Red, reaching as high as 26.46 mmol⋅g^-1⋅h^-1 and 32.85 mmol⋅g^-1 ⋅h^-1, respectively, which is 2-3 times greater than that observed in pure water and is 10 times greater than most reported studies. The great significance of this work lies in the potential for efficient H₂ production through the utilization of wastewater.