Das, S., Zhang, J., Ang, Z. Z., Boong, S. K., Ng, L. S., Raja Mogan, T., & Lee, H. K. (2026). Phosphorus–carbon nitride hybridization enables spatial co-localization of electrons and reactants for enhancing metal-free nitrogen photofixation. Chemical Engineering Journal, 529, 173005. https://doi.org/10.1016/j.cej.2026.173005
Abstract:
Photocatalytic nitrogen reduction reaction (NRR) presents a sustainable approach for ammonia synthesis under ambient conditions using light energy, offering a greener alternative to the energy-intensive Haber-Bosch process. However, conventional photocatalysts, especially metal-free systems, often suffer from inefficient charge separation, poor N2 adsorption, and limited surface reactivity. Here, we introduce a phosphorus-doped graphitic carbon nitride (PCN) photocatalyst that enables efficient nitrogen photofixation into ammonia even without the need for metal co-catalysts or sacrificial agents. Our design integrates two key synergistic effects. First, phosphorus doping introduces midgap states into the g-C3N4 electronic structure, thereby promoting photocarrier separation and directional electron migration toward phosphorus-rich domains. Second, chemical hybridization between phosphorus and nitrogen atoms enhances the electrophilicity and polarizability of phosphorus sites, which improves N2 adsorption and activation. This co-localization of photogenerated electrons and nitrogen reactants at active phosphorus sites enables efficient nitrogen-to-ammonia photoconversion. Notably, the optimized PCN-3 photocatalyst achieves an ammonia production rate of ∼90 μmol g−1 h−1, outperforming pristine g-C3N4 by >15-fold and surpassing emerging metal-based systems by up to 37-fold. By strategically converging photogenerated charge carriers and reactant molecules, our metal-free photocatalytic design establishes an effective route for sustainable light-to-chemical energy conversion to enable efficient green ammonia production under ambient conditions.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research - Manufacturing, Trade, and Connectivity Individual Research Grants
Grant Reference no. : MTC IRG M23M6c0098
This research / project is supported by the Ministry of Education, Singapore - Academic Research Fund Tier 1
Grant Reference no. : RG92/24
This research / project is supported by the Nanyang Technological University - Start-up Grant
Grant Reference no. :