Abstract：
Low-range light absorption and rapid recombination of photo-generated charge carriers have prevented the occurrence of effective and applicable photocatalysis for decades. Quantum dots (QDs) offer a solution due to their size-controlled photon properties and charge separation capabilities. Herein, well-dispersed interstitial nitrogen-doped TiO2 QDs with stable oxygen vacancies (N-TiO2-x-VO) are fabricated by using a low-temperature, annealing-assisted hydrothermal method. Remarkably, electrostatic repulsion prevented aggregation arising from negative charges accumulated in situ on the surface of N-TiO2-x-VO, enabling complete solar spectrum utilization (200-800 nm) with a 2.5 eV bandgap. Enhanced UV-vis photocatalytic H2 evolution rate (HER) reached 2757 µmol g-1 h-1, 41.6 times higher than commercial TiO2 (66 µmol g-1 h-1). Strikingly, under visible light, HER rate was 189 µmol g-1 h-1. Experimental and simulated studies of mechanisms reveal that VO can serve as an electron reservoir of photo-generated charge carriers on N-doped active sites, and consequently, enhance the separation rate of exciton pairs. Moreover, the negative free energy (-0.35 V) indicates more favorable thermodynamics for HER as compared with bulk TiO2 (0.66 V). This research work paves a new way of developing efficient photocatalytic strategies of HER that are applicable in the sustainable carbon-zero energy supply.
摘要：
几十年来，低范围光吸收和光生电荷载流子的快速重组阻止了有效和适用的光催化的发生。量子点(QD)由于其尺寸受控的光子特性和电荷分离能力而提供解决方案。在这里，通过使用低温制备具有稳定氧空位的良好分散的间隙氮掺杂TiO2量子点（N-TiO2-x-VO），退火辅助水热法。值得注意的是,静电排斥可防止N-TiO2-x-VO表面原位积累的负电荷引起的聚集，实现完整的太阳光谱利用（200-800nm）与2.5eV的带隙。增强的UV-vis光催化H2释放速率（HER）达到2757µmolg-1h-1，比商业TiO2（66µmolg-1h-1）高41.6倍。引人注目的是，在可见光下,HER速率为189μmolg-1h-1。机理的实验和模拟研究表明，VO可以作为N掺杂活性位点上的光生电荷载流子的电子储库，因此，提高激子对的分离率。此外，与本体TiO2(0.66V)相比,负自由能(-0.35V)表明HER的热力学更有利。这项研究工作为开发适用于可持续零碳能源供应的HER高效光催化策略铺平了道路。
