Heterointerface engineering of highly dispersed Co2P on polyethyleneimine-stabilized N-doped rGO for efficient formic acid dehydrogenation

● Highly dispersed Co 2 P anchored onto PEI-stabilized N-rGO layers. ● Gas production rate of 517 mL g −1 h −1 with 100% H 2 selectivity. ● Uniform heterointerface with highly accessible interfacial sites. ● Energy barrier reduction by optimized electronic modulation of interfacial Co δ+ . Heterointerface engineering is an effective strategy for constructing strong metal–support interactions and regulating the electronic structure of metal active centers. In this study, the two-dimensional (2D) architecture of N-doped reduced graphene oxide (N-rGO) was employed to construct a uniform and highly accessible heterointerface with Co 2 P nanoparticles, thereby optimizing the electronic structure of Co 2 P for efficient hydrogen production from liquid-phase formic acid (FA). Specifically, polyethyleneimine (PEI) was introduced to stabilize the layered structure of rGO during calcination by intercalating between GO sheets, along with interacting with functional groups on GO via electrostatic interactions and hydrogen bonding. Meanwhile, PEI served as a nitrogen source to promote N doping of rGO and increase effective anchoring sites, such as pyridinic N. The resulting Co 2 P@N-rGO (PEI&phen) catalyst simultaneously achieved high Co 2 P dispersion, exposed interfacial sites, and efficient electron transfer, thereby exhibiting excellent FA dehydrogenation activity with a gas generation rate of 517 mL g −1 h −1 and H 2 selectivity of 100%. This activity was significantly higher than that of the PEI-free counterpart, in which the N-rGO structure was severely damaged, and also exceeded the activities reported for some noble-metal catalysts (e.g., Pd/C, Pt/C) and single-atom cobalt catalysts. XPS characterization and density functional theory (DFT) calculations demonstrated that the abundant Co–N interfacial sites in Co 2 P@N-rGO (PEI&phen) induced interfacial charge redistribution and optimized the electronic structure of Co 2 P species. In situ DRIFTS and DFT calculations confirmed that FA dehydrogenation over this catalyst proceeded through a formate (HCOO*) pathway, while the construction of the Co 2 P/N-rGO heterointerface significantly lowered the energy barrier of the key reaction step, thereby enhancing the catalytic activity. Download: Download high-res image (248KB) Download: Download full-size image