Photocatalytic H2O-to-H2O2 and -H2 affected by PdTiO2-δ/TiO2

The 21st Conference of Parties suggested that a significant increase in solar-driven electricity could assist in the practicable reduction of the continuously increasing global CO2 concentrations. Since the conversion efficiencies of TiO2 for photocatalytic H2O-to-H2O2 were relatively low (ie, 0.14 mmole H2O2/ gTiO(2)/min), the novel Pd-TiO2-delta/TiO2 photocatalysts for H2O-to-H2O2 and -H-2 were, thus, prepared by dispersion of palladium (36-86 ppm) on the Ti3+ self-doped TiO2 (Pd-TiO2-delta/TiO2). Specifically, a feasibility study for photocatalytic H2O(l)-to-H2O2(aq) and -H-2(g) affected by the Pd-TiO2-delta/TiO2 photocatalysts for green energy was carried out in the present work. Note that H2O2 and H-2 can be yielded through the photocatalytic two-electron transfer reactions (O-2 + 2H(+) + 2e(-) -> 2H(2)O(2) and 2H(+) +2e(-) -> H-2) that are thermodynamically feasible. Palladium on TiO2 surfaces could effectively retard the recombination of photoexcited charges and facilitated the simultaneous formation of H2O2 and H-2 from H2O. The photoactive Ti4+ on the TiO2 surface could form peroxo-species (Ti-4(+)-O2H-) that further induced the formation of H2O2. In the presence of the Pd-TiO2-delta/TiO2 photocatalyst, under UV light irradiation for 90 min, very high yields of naturally separated H2O2(aq) (0.45 mmole/gTiO(2)/ min) and H-2(g) (0.16 mmole/gTiO(2)/min) could be obtained simultaneously. A relatively high photo-conversion efficiency (14%) for the Pd-TiO2-delta/TiO2 photocatalysts was achieved. This work demonstrates that using the unlimited solar energy, the effective Pd-TiO2-delta/TiO2 photocatalysts can enhance H2O(l)-to-H2O2(aq) and -H-2(g) for green energy.