Pressure-Optimized Band Gap and Enhanced Photoelectric Response of Graphitic Carbon Nitride with Nitrogen Vacancies
Pressure-Optimized Band Gap and Enhanced Photoelectric Response of Graphitic Carbon Nitride with Nitrogen Vacancies
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DOI：
10.1103/physrevapplied.19.024048
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发表时间：
2023-02-16
影响因子：
4.6
通讯作者：
Ding, Junfeng
中科院分区：
文献类型：
--
作者：
Cheng, Peng;Yao, Deyuan;Ding, Junfeng
石墨化碳氮化物(g-C3N4)作为光催化剂具有良好的性能，近年来引起了人们的广泛关注。由于其2.70 eV的宽带隙限制了可见光的吸收，人们已经做了很多努力来优化带隙。在这份报告中，压力被用来控制缺氮g-C3N4纳米薄片的带隙和光电响应。由于氮空位的引入，样品的带隙首先缩小到2.40 eV，然后在压力下进一步减小到1.70 eV，这是文献中报道的未掺杂g-C3N4的最低值。相应地，由于高压下光吸收的增强，光电响应增加了近50%。更有趣的是，在降压到环境压力后，优化的带隙仍然存在，最小值为1.87 eV，并伴随着增强的光电响应性。原位同步X射线衍射谱和拉曼光谱表明，可调谐禁带来源于g-C3N4空位的不可逆压致非晶化。这里采用的引入缺陷和加压处理的联合方法显示了在比单一带隙收窄技术显著更宽的区域内连续设计带隙的能力，从而提高了加宽半导体的光电性能。
Graphitic carbon nitride (g-C3N4) shows favorable performance as a photocatalyst and has attracted widespread attention in recent years. As its wide band gap of 2.70 eV limits light absorption in the visible range, many efforts have been made to optimize the band gap. In this report, pressure is used to engineer the band gap and photoelectric response of nitrogen-deficient g-C3N4 nanoflakes. The band gap of the sample is first narrowed to 2.40 eV due to the introduction of nitrogen vacancies and then further nar-rowed to 1.70 eV by pressure, which is the lowest value reported in the literature for undoped g-C3N4. Accordingly, the photoelectric response increases by nearly 50% because of the enhanced light absorp-tion at high pressure. More interestingly, after depressurization to ambient pressure, the optimized band gap survives with a minimum value of 1.87 eV accompanied by enhanced photoelectric responsivity. In situ synchrotron x-ray diffraction and Raman spectra suggest that the tunable band gap originates from irreversible pressure-induced amorphization with the assistance of vacancies for g-C3N4. The collabora-tive approach of introducing deficiency and pressure treatment adopted here shows the ability to engineer the band gap continuously over a prominently wider region than that for the single band-gap-narrowing technique, and thus, enhances the photoelectric performance for broadened semiconductors.