Efficient and selective photocatalytic CH(4) conversion to CH(3)OH with O(2) by controlling overoxidation on TiO(2)

The conversion of photocatalytic methane into methanol in high yield with selectivity remains a huge challenge due to unavoidable overoxidation. Here, the photocatalytic oxidation of CH(4) into CH(3)OH by O(2) is carried out on Ag-decorated facet-dominated TiO(2). The {001}-dominated TiO(2) shows a durable CH(3)OH yield of 4.8 mmol g(−1) h(−1) and a selectivity of approximately 80%, which represent much higher values than those reported in recent studies and are better than those obtained for {101}-dominated TiO(2). Operando Fourier transform infrared spectroscopy, electron spin resonance, and nuclear magnetic resonance techniques are used to comprehensively clarify the underlying mechanism. The straightforward generation of oxygen vacancies on {001} by photoinduced holes plays a key role in avoiding the formation of •CH(3) and •OH, which are the main factors leading to overoxidation and are generally formed on the {101} facet. The generation of oxygen vacancies on {001} results in distinct intermediates and reaction pathways (oxygen vacancy → Ti–O(2)(•) → Ti–OO–Ti and Ti–(OO) → Ti–O(•) pairs), thus achieving high selectivity and yield for CH(4) photooxidation into CH(3)OH.