Regulating bimetallic active centers for exploring the structure-activity relationship upon high-performance photocatalytic nitrogen reduction

Photocatalytic ammonia (NH3) synthesis from N2 is a strategy conducive to carbon neutrality because it avoids high energy consumption and high carbon emission process in the industrial synthesis of NH3. However, the structure-activity relationship of bimetallic active centers in heterogeneous catalysts is still dimness for high-performance photocatalytic nitrogen reduction reaction (pNRR). Here, a rational N2-bridging strategy for heterogeneously pNRR has been expanded through regulating bimetallic Ti-Pd active centers at TiO2 (101)/Pd (111) interface and the structure-activity correlation during the pNRR was explored. The side-on adsorption with “*N ≡ N*” configuration (*presents the adsorption site) on Ti-Pd centers induces a considerable polarization and potent activation of N2, enabling to achieve an impressive rate of NH3 production (635.73 µg gcat.−1 h− 1) on the optimal se-Pd/m-TiO2 NRs (2.71%). More importantly, nearly ~ 92.37% of initial activity could be retained following 8 successive reaction rounds. Further mechanism studies revealed that the side-on bridging mode of N2 with bimetallic Ti-Pd centers possesses an ultra-high adsorption energy, which can effectively weaken the triple bond of N2 and reduce the activation energy barrier of pNRR process. This study provides insights into the electronic structure regulation of bimetallic active centers and structure-property relationship at the atomic level.