AbstractThe electrochemical nitrogen reduction reaction (ENRR) is regarded as a potential alternative to produce ammonia under ambient conditions. However, the lack of powerful electrocatalysts and the non‐negligible hydrogen evolution reaction (HER) have become a bottleneck of further development of ENRR. In this work, [Mo3S13]2− clusters were introduced onto 2D‐structured Pd nanosheets (NSs) to form Pd−S−Mo NSs with abundant Mo active sites for N2 activation. A Faradaic efficiency (FE) of 10.7 % was realized by Pd−S−Mo NSs on hydrophilic carbon support, superior to their single‐component counterparts. Furthermore, loading Pd−S−Mo NSs on hydrophobic hierarchical graphene support was carried out to suppress HER, achieving a FE of 23.8 % and improved ammonia yield. This work provides a designed principle of efficient ENRR electrocatalysts by engineering Mo active sites and catalyst supports.