Laboratory of Advanced Materials, Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , Shanghai 200433, China.
Key Laboratory of Computational Physical Sciences, Ministry of Education, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University , Shanghai 200433, China.
ACS Appl Mater Interfaces. 2016 May 25;8(20):12772-9. doi: 10.1021/acsami.6b01534. Epub 2016 May 12.
Despite the recent progress of developing graphitic carbon nitride (g-C3N4) as a metal-free photocatalyst, the synthesis of nanostructured g-C3N4 has still remained a complicated and time-consuming approach from its bulk powder, which substantially limits its photoelectrochemical (PEC) applications as well as the potential to form composites with other semiconductors. Different from the labor-intensive methods used before, such as exfoliation or assistant templates, herein, we developed a facile method to synthesize graphitic C3N4 quantum dots (g-CNQDs) directly grown on TiO2 nanowire arrays via a one-step quasi-chemical vapor deposition (CVD) process in a homemade system. The as-synthesized g-CNQDs uniformly covered over the surface of TiO2 nanowires and exhibited attractive photoluminescence (PL) properties. In addition, compared to pristine TiO2, the heterojunction of g-CNQD-decorated TiO2 nanowires showed a substantially enhanced PEC photocurrent density of 3.40 mA/cm(2) at 0 V of applied potential vs Ag/AgCl under simulated solar light (300 mW/cm(2)) and excellent stability with ∼82% of the photocurrent retained after over 10 h of continuous testing, attributed to the quantum and sensitization effects of g-CNQDs. Density functional theory calculations were further carried out to illustrate the synergistic effect of TiO2 and g-CNQD. Our method suggests that a variety of g-CNQD-based composites with other semiconductor nanowires can be synthesized for energy applications.
尽管最近在开发无金属石墨相氮化碳（g-C3N4）作为光催化剂方面取得了进展，但从块状粉末合成纳米结构的 g-C3N4 仍然是一个复杂且耗时的过程，这极大地限制了其光电化学（PEC）应用以及与其他半导体形成复合材料的潜力。与以前使用的费力方法（例如剥离或辅助模板）不同，本文通过在自制系统中进行一步准化学气相沉积（CVD）过程，直接在 TiO2 纳米线阵列上合成了石墨化 C3N4 量子点（g-CNQDs）。合成的 g-CNQDs 均匀覆盖在 TiO2 纳米线表面，并表现出有吸引力的光致发光（PL）特性。此外，与原始 TiO2 相比，g-CNQD 修饰的 TiO2 纳米线异质结在模拟太阳光（300 mW/cm2）下施加 0 V 偏压时表现出 3.40 mA/cm2 的显著增强的 PEC 光电流密度，并且在 10 小时以上的连续测试后保留了约 82%的光电流，这归因于 g-CNQDs 的量子和敏化效应。进一步进行了密度泛函理论计算以说明 TiO2 和 g-CNQD 的协同效应。我们的方法表明，可以合成具有其他半导体纳米线的各种基于 g-CNQD 的复合材料，用于能源应用。
