Electron pump strengthened facet engineering: Organic half-metallic C(CN)3 enclosed (100) facet exposed WO3 for efficient and selective photocatalytic nitrogen fixation

Abstract

Boosting the replacement of traditional NH3 production (Haber–Bosch process) with photocatalytic technology is of great importance for energy and environment remediation. Herein, electron pump strengthened facet engineering is firstly proposed by integration of organic half metallic C(CN)3 on (100) and (110) facet exposed WO3 nanosheets and nanowires. The different built-in electric field is constructed at the interface of the composites. For WO3 nanosheets based WsC, the photoinduced electrons can be directly pumped on the reactive sties of C(CN)3 which performs as the first organic cocatalyst for N2 fixation. While for WO3 nanowires based WwC, the electrons transfer from C(CN)3 to WO3 nanowires, which is unfavorable for the photocatalytic N2 fixation. This process is dedicatedly visualized by Kelvin Probe Force Microscopy (KPFM). As a result, the NH3 evolution yield of optimized WsC reaches 81.9 μmol·gcat−1, which is 4.7 folds of the C(CN)3 enwrapped WO3 nanowires (WwC). Moreover, the performance of C(CN)3 surpasses the reported Au, Pt and Ru noble metal cocatalysts. In-situ DRIFTS spectra and DFT calculations also demonstrate the superiorities of C(CN)3 collaborated with facet engineering. This electron pump strengthened facet engineering with C(CN)3 may open up new opportunities for metal-free polymer-based photocatalytic systems for N2 photofixation.