Oxo dicopper anchored on carbon nitride for selective oxidation of methane.

Xie, Pengfei; Ding, Jing; Yao, Zihao; Pu, Tiancheng; Zhang, Peng; Huang, Zhennan; Wang, Canhui; Zhang, Junlei et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Selective conversion of methane (CH<sub>4</sub>) into value-added chemicals represents a grand challenge for the efficient utilization of rising hydrocarbon sources. We report here dimeric copper centers supported on graphitic carbon nitride (denoted as Cu<sub>2</sub>@C<sub>3</sub>N<sub>4</sub>) as advanced catalysts for CH<sub>4</sub> partial oxidation. The copper-dimer catalysts demonstrate high selectivity for partial oxidation of methane under both thermo- and photocatalytic reaction conditions, with hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and oxygen (O<sub>2</sub>) being used as the oxidizer, respectively. In particular, the photocatalytic oxidation of CH<sub>4</sub> with O<sub>2</sub> achieves >10% conversion, and >98% selectivity toward methyl oxygenates and a mass-specific activity of 1399.3 mmol g Cu<sup>-1</sup>h<sup>-1</sup>. Mechanistic studies reveal that the high reactivity of Cu<sub>2</sub>@C<sub>3</sub>N<sub>4</sub> can be ascribed to symphonic mechanisms among the bridging oxygen, the two copper sites and the semiconducting C<sub>3</sub>N<sub>4</sub> substrate, which do not only facilitate the heterolytic scission of C-H bond, but also promotes H<sub>2</sub>O<sub>2</sub> and O<sub>2</sub> activation in thermo- and photocatalysis, respectively.