Multi-electron reduction process for boosting ammonia photosynthesis using graphene-modified red phosphorus

Abstract

As a green and sustainable approach, nitrogen photofixation makes a strong contribution in suppressing the energy crisis. Boosting ammonia photosynthesis efficiency without additional sacrificial agents remains a significant challenge. In this study, an electron-rich reduced graphite oxide-modified red phosphorus (rGORP) was synthesized for ammonia visible-light photo-production. The rGORP composite retained the lattice structure of RP, activating NN through the acceptance and donation of electrons during nitrogen photofixation. Moreover, the incorporation of rGO increased the number of lone pairs of electrons and optimized the band structure of rGORP as well. Benefiting from appropriate conduction band, sufficient electrons, and effective electron transfer in 0.02rGORP (0.02 is the mass ratio of rGO to RP), activated N2 could be reduced into ammonia by a simultaneous three-electron reduction process, with a high ammonia synthesis rate of 7.74 mg/(L⋅h) without any organic scavengers. The system restricted the intermediate products formation and elevated the photocatalytic efficiency, thereby extending the application of non-metal materials in nitrogen photofixation.