Response of seed priming with boron on germination and seedling sprouts of broccoli.

Abstract

Selective conversion of methane (CH₄) 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 Cu₂@C₃N₄) as advanced catalysts for CH₄ partial oxidation. The copper-dimer catalysts demonstrate high selectivity for partial oxidation of methane under both thermo- and photocatalytic reaction conditions, with hydrogen peroxide (H₂O₂) and oxygen (O₂) being used as the oxidizer, respectively. In particular, the photocatalytic oxidation of CH₄ with O₂ achieves >10% conversion, and >98% selectivity toward methyl oxygenates and a mass-specific activity of 1399.3 mmol g Cu^-1h^-1. Mechanistic studies reveal that the high reactivity of Cu₂@C₃N₄ can be ascribed to symphonic mechanisms among the bridging oxygen, the two copper sites and the semiconducting C₃N₄ substrate, which do not only facilitate the heterolytic scission of C-H bond, but also promotes H₂O₂ and O₂ activation in thermo- and photocatalysis, respectively.