Du Huihui, Gao Xinhua, Ma Qingxiang, Yang Xiaojiao, Zhao Tian-Sheng
State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry & Chemical Engineering, Ningxia University, Yinchuan 750021, China.
ACS Omega. 2022 May 2;7(19):16817-16826. doi: 10.1021/acsomega.2c01827. eCollection 2022 May 17.
g-CN-based materials show potential for photoreduction of CO to oxygenates but are subjected to fast recombination of photogenerated charge carriers. Here, a novel Cu-dispersive protonated g-CN (PCN) metal-semiconductor (m-s) heterojunction from thermal reduction of a CuO/PCN precursor was prepared and characterized using in situ X-ray diffraction, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible (UV-vis) spectra, photoluminescence (PL) spectra, transient photocurrent response, and electrochemical impedance spectroscopy (EIS). The Cu amount in Cu/PCN and the reduction temperature affected the generation of CHOH and CHOH from the photoreaction of CO-aerated HO. During calcination of CuO/PCN in N at 550 °C, CuO was completely reduced to Cu with even dispersion, and a m-s heterojunction was obtained. With thermal exfoliation, Cu/PCN showed a specific surface area and layer spacing larger than those of PCN. Cu/PCN-0.5 (12.8 wt % Cu) exhibited a total carbon yield of 25.0 μmol·g under UV-vis irradiation for 4 h, higher than that of CuO/PCN (13.6 μmol·g) and PCN (6.0 μmol·g). The selectivity for CHOH and CHOH was 51.42 and 46.14%, respectively. The PL spectra, transient photocurrent response, and EIS characterizations indicated that Cu/PCN heterojunction promotes the separation of electrons and holes and suppresses their recombination. The calculated conduction band position was more negative, which is conducive to the multielectron reactions for CHOH and CHOH generation.
基于g-CN的材料在将CO光还原为含氧化合物方面显示出潜力，但会受到光生电荷载流子的快速复合影响。在此，通过对CuO/PCN前驱体进行热还原制备了一种新型的Cu分散质子化g-CN（PCN）金属-半导体（m-s）异质结，并使用原位X射线衍射、扫描透射电子显微镜、X射线光电子能谱、紫外-可见（UV-vis）光谱、光致发光（PL）光谱、瞬态光电流响应和电化学阻抗谱（EIS）对其进行了表征。Cu/PCN中的Cu含量和还原温度影响了CO曝气的H₂O光反应生成CH₃OH和C₂H₅OH的过程。在550℃的N₂气氛中煅烧CuO/PCN时，CuO完全还原为均匀分散的Cu，并获得了一个m-s异质结。通过热剥离，Cu/PCN的比表面积和层间距比PCN更大。Cu/PCN-0.5（12.8 wt% Cu）在紫外-可见光照射4小时下的总碳产率为25.0 μmol·g，高于CuO/PCN（13.6 μmol·g）和PCN（6.0 μmol·g）。对CH₃OH和C₂H₅OH的选择性分别为51.42%和46.14%。PL光谱、瞬态光电流响应和EIS表征表明，Cu/PCN异质结促进了电子和空穴的分离，并抑制了它们的复合。计算得到的导带位置更负，这有利于生成CH₃OH和C₂H₅OH的多电子反应。
