Bipolar system induced surface electronic localization of violet phosphorene for CO2 photoreduction to ethylene

The photocatalytic CO 2 reduction (CO 2 RR) to high-value-added chemicals such as ethylene (C 2 H 4 ) is desirable but challenging, due to the easy desorption of C 1 intermediates and insufficient C C coupling to C 2 intermediates. The CO 2 RR performance of violet phosphorus (VP) could be significantly altered by its electronic configurations, especially for C 2 H 4 selectivity. Herein, the effective electronic localization engineering of VP has been achieved by a well spatially dispersed dual-cocatalyst modification (VP-PA-Co₂P-Ag). The well distributed Co 2 P nanoflocs modification on VP were realized by prefunctionalization treatment of VP with phytic acid (PA). The metallic Co₂P and Ag were found to serve as bipolar system to induce more efficient surface electronic localization of VP and electronic enrichment on Co sites. The adsorption and activation of CO 2 , absorption and coupling of intermediates (CO ⁎ , CHO ⁎ ), and separation dynamics of photogenerated carriers have been demonstrated to be enhanced due to the significant orbital hybridization between CO 2 and Co 3d , which owing to the electronic localization on Co sites. Therefore, the C C coupling activity and selectivity on VP-PA-Co₂P-Ag has been demonstrated to be enhanced significantly to achieve 14.6 μmol g −1  h −1 and 69.9% electron selectivity of C 2 H 4 without any hole-sacrificial agent. The selective photocatalytic CO 2 -to-C 2 H 4 mechanism has been explored by in-situ diffuse reflectance infrared Fourier-transform, in-situ X-ray photoelectron spectroscopy, femtosecond ultrafast transient absorption, density of states, and Gibbs free-energy profiles, where the CO ⁎ intermediates could be easily adsorbed for protonation (CHO ⁎ ) and further C C coupling (COCHO ⁎ ), continuously reduced by successive proton-coupled multielectron transfer process to yield C 2 H 4 .