Selective CH4 Reform to Methanol Through Partial Oxidation over Bi2O3 at Room Temperature and Pressure

Herein, we propose that an efficient CH 4 partial photooxidation to methanol depends on appropriate band edge positions in photocatalysts. We demonstrated our hypothesis using Bi 2 O 3 since this semiconductor have a valence band favorable to produce •OH and a conduction band not advantageous to O 2 • - which is crucial to keep O 2 available for •CH 3 capture and CH 3 OH formation. A notably and selective partial photooxidation of methane to methanol was observed under visible light at room temperature and pressure. As a result, the productivity of methanol over Bi 2 O 3 can reach approximately 3,771 μmol g -1 h -1 with c.a. 65% selectivity avoiding overoxidation to CO 2 . Isotope labeling experiment ( 13 CH 4 ) confirmed that methane acts as the carbon source of methanol and ESR measurements proved the •CH 3 and •OH generation. Besides, Bi 2 O 3 exhibited good stability after 5 cycles maintaining a high and selective methanol production. These results provide insight into critical photocatalyst properties for the partial photooxidation of methane to methanol. • Controlled photooxidation of methane to methanol. • Methane reform under mild conditions. • O 2 plays a key role in the methanol formation. • The semiconductor must have a valence band favorable to •OH. • The semiconductor must have a conduction band not advantageous to O 2 • - .