Photon-driven chemical processes are usually mediated by oxides, nitrides and sulfides whose photo-conversion efficiency is limited by charge carrier recombination. Here we show that lithium hydride undergoes photolysis upon ultraviolet illumination to yield long-lived photon-generated electrons residing in hydrogen vacancies, known as F centres. We demonstrate that photon-driven dehydrogenation and dark rehydrogenation over lithium hydride can be fulfilled reversibly at room temperature, which is about 600 K lower than the corresponding thermal process. As light-driven F centre generation could provide an alternative approach to charge carrier separation to favour chemical transformations that are kinetically or thermodynamically challenging, we show that light-activated lithium hydride cleaves the N≡N triple bond to form a N–H bond under mild conditions. Co-feeding a N₂/H₂ mixture with low H₂ partial pressure leads to photocatalytic ammonia formation at near ambient conditions. This work provides insights into the development of advanced materials and processes for light harvesting and conversion.

光子驱动的化学过程通常由氧化物、氮化物和硫化物介导，其光转换效率受到载流子复合的限制。在这里，我们展示了氢化锂在紫外线照射下发生光解，产生驻留在氢空位（称为 F 中心）中的长寿命光子产生的电子。我们证明了氢化锂上的光子驱动脱氢和暗再氢化可以在室温下可逆地完成，这比相应的热过程低约 600 K。由于光驱动的 F 中心生成可以提供另一种电荷载流子分离方法，以有利于在动力学或热力学上具有挑战性的化学转化，因此我们表明，光激活的氢化锂在条件温和。共同进料具有低H ₂分压的N ₂ /H ₂混合物导致在接近环境条件下光催化氨的形成。这项工作为光采集和转换的先进材料和工艺的开发提供了见解。