Atomically Dispersed Nickel Anchored on a Nitrogen-Doped Carbon/TiO2 Composite for Efficient and Selective Photocatalytic CH4 Oxidation to Oxygenates

Direct photocatalytic oxidation of methane to liquid oxygenated products is a sustainable strategy for methane valorization at room temperature. However, in this reaction, noble metals are generally needed to function as cocatalysts for obtaining adequate activity and selectivity. Here, we report atomically dispersed nickel anchored on a nitrogendoped carbon/TiO2 composite (Ni-NC/TiO2) as a highly active and selective catalyst for photooxidation of CH4 to Cl oxygenates with O-2 as the only oxidant. Ni-NC/TiO2 exhibits a yield of Cl oxygenates of 198 umol for 4 h with a selectivity of 93 %, exceeding that of most reported high-performance photocatalysts. Experimental and theoretical investigations suggest that the single-atom Ni-NC sites not only enhance the transfer of photogenerated electrons from TiO2 to isolated Ni atoms but also dominantly facilitate the activation of O-2 to form the key intermediate center dot OOH radicals, which synergistically lead to a substantial enhancement in both activity and selectivity.

Automated summary

Direct photocatalytic oxidation of methane to liquid oxygenated products at room temperature is achieved using atomically dispersed nickel anchored on a nitrogen-doped carbon/TiO2 composite (Ni-NC/TiO2) catalyst. The Ni-NC/TiO2 catalyst exhibits high activity and selectivity for the formation of Cl oxygenates, with a yield of 198 umol and a selectivity of 93% in 4 hours. The enhanced performance is attributed to the presence of single-atom Ni-NC sites that facilitate electron transfer and activate O2 to form reactive oxygen species.