Xingxing Huang,Yingzhang Shi,Cheng Liu,Zhiwen Wang,Jinhong Bi,Jimmy C. Yu,Ling Wu
A series of Cu 2 O clusters/MIL-100(Fe) heterojunctions with different Cu 2 O mass ratios were constructed as the photocatalysts for N 2 fixation. An optimal nitrogen fixation performance of 51.22 μmol·g −1 ·h −1 is achieved when the mass fraction of Cu 2 O is 20 %. Isotope analysis experiments confirmed that the nitrogen source is N 2 . Possible intermediate signals during photocatalytic reactions were detected by in situ DRIFTS. XPS results further confirm the formation of Cu 2 O/MIL-100(Fe) heterojunctions, and that the existence of Cu–O surface interactions is the key to efficient electron transfer. It is revealed that the improvement of the catalytic performance is derived from the formation of heterojunction which regulates the energy band structure as well as promotes the separation of photogenerated electron-hole pairs. This study proposes a possible mechanism of photocatalytic nitrogen fixation and emphasizes the role of surface interaction and electron transfer in type-II heterojunction in improving nitrogen fixation performance.
The oligomers of carbon suboxide, known as red carbon, exhibit a highly conjugated structure and semiconducting properties. Upon mild heat treatment, it transforms into a carbonaceous framework rich in oxygen surface terminations, called oxocarbon. In this study, the abundant oxygen functionalities are harnessed as anchors to create oxocarbon-supported nanohybrid electrocatalysts. Starting with single atomic Cu (II) strongly coordinated to oxygen atoms on red carbon, the Fehling reaction leads to the formation of Cu 2 O clusters. Simultaneously, a covalent oxocarbon framework emerges via cross-linking, providing robust support for Cu 2 O clusters. Notably, the oxocarbon support effectively stabilizes Cu 2 O clusters of very small size, ensuring their high durability in acidic conditions and the presence of ammonia. The synthesized material exhibits a superior electrocatalytic activity for nitrate reduction under acidic electrolyte conditions, with a high yield rate of ammonium (NH 4 + ) at 3.31 mmol h −1 mg cat −1 and a Faradaic efficiency of 92.5% at a potential of −0.4 V (vs RHE).
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