Electrochemical nitrogen reduction reaction (NRR) under ambient conditions offers an environmentally benign and sustainable alternative for NH3 synthesis. Exploring highly active and robust NRR electrocatalysts is one of the prerequisites for developing sustainable N-2/NH3 cycle systems. In this work, a surface chemistry rich TiO2/CeO2 frame is developed for electrochemical NRR, which is composed of ultrathin TiO2 nanosheets supported with CeO2 nanoparticles. Its unique porous framework as well as formed plentiful oxygen vacancies (OVs) and hetero-interfaces collectively facilitate the adsorption/activation of N-2 and transfer of electrons and protons. The catalyst can attain a high NH3 yield rate of 8.8 mu g h(-1) mg(cat.)(-1) and a Faradaic efficiency of 6.8 % at -0.25 V versus reversible hydrogen electrode, comparable with other reported Ti-based and OVs-contained catalysts. Moreover, the TiO2/CeO2 can maintain high durability over repeated 20 cycles. Therefore, this work heralds a new paradigm of fabricating framework-structured catalyst with enriched hetero-interfaces and defects toward effective and sustainable NH3 synthesis.

Despite the direct utilizing metal-organic frameworks (MOFs) as promising photocatalysts for H2O2 production, their activity and selectivity are still undesirable owing to the insufficient active centers, weak visible-light absorption, and limited charge transfer. Herein, the Ce-doped Ti-based MOFs MIL-125-NH2 photocatalysts (Ce/TiMOFs) were synthesized by a facile impregnation-coordination method, during which the doped Ce species could not only extend the visible-light absorption edge but also provide new reactive sites for promoting the charge transfer and selectivity of two-electron O-2 reduction. Interestingly, the optimal Ce/TiMOFs-0.010 achieved a rate of H2O2 yield of 2464 mu M h(-1) g(-1) with similar to 3.4-fold improvement compared to TiMOFs, attributed to the faster conversion rate of the main reactive oxygen intermediates (O-center dot(2)-) and improved average transfer electron number. This work provides an effective strategy to optimize the photocatalytic performances of MOFs and expands the application of MOFs in the sustainable energy production field.

Ce-doped MIL-125-NH2 photocatalysts (Ce/TiMOFs) were synthesized by a facile impregnation-coordination method, during which the doped Ce species could not only extend the visible-light absorption edge but also provide new reactive sites for promoting the charge transfer and selectivity of two-electron O2 reduction. The optimal Ce/TiMOFs-0.010 achieved a rate of H2O2 yield of 2464 μM h-1 g-1 with ∼3.4-fold improvement compared to TiMOFs, attributed to the faster conversion rate of the main reactive oxygen intermediates (⋅O2-) and improved average transfer electron number. More information can be found in the Research Article by Baolin Yan et al.