Nickel phosphide nanoparticles as a noble-metal-free co-catalyst for the selective photocatalytic aerobic oxidation of CH4 into CO and H2

• Published in: Journal of catalysis Vol. 425; pp. 306 - 313
• Main Authors: Chai, Yao, Tang, Sishi, Wang, Qiang, Wu, Qiong, Li, Li, Liang, Jun
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2023
• Subjects: Carbon monoxide; NiP2/TiO2 photocatalyst; Photocatalysis; Selective oxidation of methane; Superoxide ions; Superoxide ions; Selective oxidation of methane; Carbon monoxide; NiP2/TiO2 photocatalyst; Photocatalysis
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2023.06.027

[Display omitted] •NiP2/TiO2 heterojunction was prepared by two steps of ion exchange method and medium temperature phosphating.•NiP2 nanoparticles are embedded within the TiO2 lattice, forming a tightly-bound heterointerface.•The NiP2/TiO2 catalyst achieves efficient catalytic conversion of CH4 to CO and H2 under full-spectrum irradiation.•NiP2 induces the activation of O2 to produce O2- cracked CH4.•The oxidation of CH4 occurs gradually along the conversion path of *CH3O → *CHO →*COOH → *CO by holes. In this study, we report the use of NiP2/TiO2 as a photocatalyst for the transformation of methane (CH4) to carbon monoxide (CO) and hydrogen (H2) under UV–visible light irradiation. As a co-catalyst, NiP2 can promote the charge separation of TiO2 on the one hand, and can effectively promote the activation of O2 to generate superoxide ions (O2–) on the other hand. O2–, as the main active species, cleaves CH4 molecules to form methoxyl radical (•CH3O). Under the influence of photogenerated holes, •CH3O gradually undergoes oxidation to form an intermediate *COOH, which is subsequently converted to CO. Meantime, H+ is reduced to form H2. Therefore, the production of CO and H2 attained 267.5 and 72.4 μmol g–1h−1 for the NiP2/TiO2-2 photocatalyst with the optimal ratio, respectively. In fact, this research showcases the capability of NiP2/TiO2 as a remarkably effective and specific photocatalyst for transforming CH4 into high-value commodities.