Yongju Hong, Sangyeon Jeong, Jae Hun Seol, Taekyung Kim, Seong Chan Cho, Tae Kyung Lee, Chaeyoen Yang, Hionsuck Baik, Hyun S. Park, Eunsoo Lee, Sung Jong Yoo,* Sang Uck Lee,* and Kwangyeol Lee* Ru2P/Ir2P Heterostructure Promotes Hydrogen Spillover for Efficient Alkaline Hydrogen Evolution Reaction Adv. Energy Mater. 2024, XX, XXXX. DOI: 10.1002/aenm.202401426 Y.H., S.J., J.H.S.,and T.K. contributed equally to this work.