Light-driven dinitrogen activation and reduction: from fundamental principles to catalyst design

To address the global energy crisis and the escalating challenge of climate change, there is an urgent need to develop mild and sustainable ammonia synthesis technologies that can replace the energy-intensive Haber-Bosch process. Photocatalytic dinitrogen reduction reaction (NRR) offers a promising, green route for converting N2 and H2O into NH3 using solar energy. However, this approach remains confronted by significant challenges, including the difficulty of activating N2 molecules, the strong competition from the hydrogen evolution reaction, and the rapid recombination of photo-generated carriers. This review systematically highlights the key strategies for augmenting the performance of photocatalytic NRR. Advances in material design, including the construction of S-type heterojunctions, the introduction of oxygen/nitrogen vacancies, the implementation of heteroatomic doping, and the regulation of nanostructures, have improved light absorption, charge separation, and N2 adsorption/activation. At the system level, it is imperative to ensure precise alignment of light sources and reactors. In addition, isotope labelling and related techniques are indispensable for the accurate quantification of NH3 yield, thereby facilitating reliable performance evaluation. Although current photocatalytic NRR efficiency and stability remain far from industrially viable, future progress will be made through the integration of in-situ characterization with theoretical simulations, multi-field coupling of light, heat and electricity, biomimetic catalyst design, and achieving full reaction synergy.