Solar-energy-driven conversion of oxygen-bearing low-concentration coal mine methane into methanol on full-spectrum-responsive WO3−x catalysts. (1st November 2021)

• Record Type: Journal Article
• Authors: Yang, Juan; Chen, Pengyu; Dai, Jun; Chen, Yumei; Rong, Liqing; Wang, Dazhao
• Is Part Of: Energy conversion and management. Volume 247(2021)
• Publication Date: 2021-11-01
• Subjects: Solar energy conversion -- Low-concentration coal mine methane -- Photocatalysis -- Methanol -- WO3−x catalysts; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2021.114767
• Languages: English
• ISSNs: 0196-8904

Abstract

Graphical abstract: Highlights: WO3−x can be utilized as full-spectrum catalysts for LC-CMM conversion into methanol. Methanol yield on WO3−x -N2.0 is 4.5 times higher than that of WO3 -A2.0 under SSL. Selective production of methanol is firstly achieved over WO3−x -N2.0 under NIR light. Forming oxygen vacancies boosts electron-hole separation and active species production. Enhanced mechanism of LC-CMM conversion on defect-rich WO3−x -N2.0 is proposed. Abstract: Sunlight-driven photocatalysis is regarded as a promising strategy for direct conversion of methane in low concentration coal mine methane (LC-CMM) to value-added methanol, yet remains a grand challenge to efficiently activate and convert methane. Herein, WO3−x nanosheets with gradient concentration of oxygen vacancy were synthesized and firstly served as full-spectrum responsive catalysts for transformation of LC-CMM to methanol at ambient conditions. Defect-rich WO3−x -N2.0 shows a methanol yield of 1475 μmol·g −1, roughly 4.5 times higher than WO3 -A2.0 under simulated solar light irradiation. The selectivity of CH3 OH on the optimal WO3−x -N2.0 is up to 76%. More importantly, WO3−x -N2.0 exhibits a methanol yield of 396 μmol·g −1 with the selectivity of 82% even under near infrared light irradiation while almost no CH3 OH is detected over WO3 -A2.0. Based on the results of energy-band structure, photoelectrochemical characterization, PLs and EPR tests, the significantly enhanced photocatalytic performance over WO3−x -N2.0 is ascribed to the synergistic effect caused by the formation of oxygen vacancies, including extending light absorption into NIR region, improving separation of photoinduced electron-hole pairs and boosting production of hydroxyl radicals (key active species that drive CH3 OH production). This work will offer a sustainable pathway to broaden the utilization of LC-CMM via efficient coupling of solar energy.