Oxygen vacancy-rich CoMoO4/Carbon nitride S-scheme heterojunction for boosted photocatalytic H2 production: Microstructure regulation and charge transfer mechanism

• Published in: Journal of materials science & technology Vol. 198; pp. 176 - 185
• Main Authors: Qin, Jiani, Dong, Yanli, Lai, Xiaojuan, Su, Bo, Pan, Bao, Wang, Chuanyi, Wang, Sibo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2024
• Subjects: Carbon nitride; CoMoO4; Oxygen vacancy; Photocatalysis; S-scheme; S-scheme; CoMoO4; Photocatalysis; Carbon nitride; Oxygen vacancy
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2024.02.032

•A novel S-scheme oxygen vacancy-rich CoMoO4/CN heterojunction was constructed.•4.6-fold increase in photocatalytic H2 evolution was achieved over the heterojunction.•Activation energy for H2O dissociation was reduced and oxygen vacancy density was enhanced.•Defect engineering and S-scheme heterostructure functioned synergistically.•In-situ characterizations and DFT calculation support S-scheme charge transfer pathway. Developing highly efficient S-scheme photocatalysts is a subject of immense interest for harnessing solar energy towards sustainable hydrogen production. Herein, a novel S-scheme heterojunction of oxygen vacancy-rich CoMoO4/CN (CMO/CN) photocatalyst was rationally constructed through loading CoMoO4 nanorods on carbon nitride (CN) nanosheets via a direct one-pot calcination method. The CMO/CN S-scheme heterojunction exhibited enhanced surface area, fine CN dispersion, rich oxygen vacancies, and accelerated charge separation/transfer efficiency, which were conducive to improving photocatalytic H2 evolution performance. Of note, the optimal 3 %CMO/CN sample displayed the highest H2 production rate of 8.35 mmol g−1 h−1, which is 4.6 folds that of pristine CN. In situ irradiated X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) characterizations confirmed the S-scheme charge transfer path between CN and CMO, which greatly promoted spatial charge separation. Density functional theory (DFT) calculations together with contact angle tests revealed the reduced activation energies for H2O dissociation and enhanced hydrophilicity of the CMO/CN. The CMO/CN photocatalysts also presented high stability and fine reusability. This work may provide insights into the combination of defect engineering and heterojunction designing for high-efficiency solar-to-chemical energy conversion. [Display omitted]