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Stable Ti 3+ Sites Derived from the Ti x O y -P z Layer Boost Cubic Fe 2 O 3 for Enhanced Photocatalytic N 2 Reduction

2021; American Chemical Society; Volume: 9; Issue: 45 Linguagem: Inglês

10.1021/acssuschemeng.1c05890

2168-0485

Zhi‐Gang She, Dongfang Han, Mengjiao Dai, Yingying Fan, Guoliang Pan, Weiqi Liang, Qitong Zheng, Dongdong Qin, Dongxue Han, Ying He, Li Niu,

Nanomaterials for catalytic reactions

Photocatalytic N2 fixation to NH3 using water as the reductant constitutes an encouraging method for synthesized ammonia (NH3) in the future, which helps to discover efficient photocatalysts for improving the sunlight utilization as well as enhancing the catalytic efficiency to N2 fixation. Hematite (α-Fe2O3), a high-stability, low-cost, natural abundance semiconductor photocatalyst, could represent a promising candidate for visible-light-driven N2-to-NH3 conversion in terms of cost-effectiveness, while the related reports are still sparse in this field. Notably, the single α-Fe2O3 photocatalyst generally suffers from a low reduction ability of photogenerated electrons; fatal electron–hole recombination and restricted surface active sites limit its photocatalytic activity specific potential N2 fixing. To solve the issues mentioned above, here, we designed a surface phosphorus doping anatase TiO2 (TixOy-Pz) layer containing stable Ti3+ sites for improving the photocatalytic N2 reduction reaction (pNRR) performance of cubic α-Fe2O3. The unsaturated Ti3+ species were induced on the TixOy-Pz layer as active sites by PH3 treating to realize high adsorption and activation of the N2 molecules. Meanwhile, some titanium metal defects formed by phosphorus doping make the structure of the catalyst more stable. Moreover, both TPD and time-resolved PL decay data prove that the Ti3+ species of Fe2O3@TixOy-Pz are active sites for N2 chemical absorption as well as N≡N triple bond cleavage. Using the advantage of surface Ti3+ sites of the TixOy-Pz layer together with interfacial coupling regarding Fe2O3@TixOy-Pz nanohybrid catalysts, N2 can be effectively photoreduced to NH3 with illumination under environmental conditions. For the N2 photoreduction using an Fe2O3@TixOy-Pz nanohybrid, the NH4+ yield velocity rate is 15.65 μmol gcat.–1 h–1, which is 9.43-fold, 5.31-fold, 8.37-fold, and 2.95-fold higher than cubic Fe2O3, Fe2O3@TiO2, Fe2O3-Pz, and TixOy-Pz, respectively. Satisfactorily, the as prepared Fe2O3@TixOy-Pz has quite good stability, and the NH3 production was still remarkably unvaried in six cycling tests. This work contributes to a feasible way for designing and synthesizing nanocomposite materials which have excellent photocatalytic N2 fixation performance.