CuNi/La₂O₂CO₃/rGO Nanocomposites: An Efficient Noble-Metal-Free Catalyst for Hydrogen Evolution from N₂H₄·H₂O

Abstract

Hydrous hydrazine (N2H4·H2O) has great potential as a convenient and safe hydrogen source for fuel cells. Tremendous efforts have been made to develop economic and efficient metal catalysts for hydrogen evolution from N2H4·H2O, but it remains a huge challenge. Herein, for the first time, noble-metal-free CuNi nanoparticles (NPs) immobilized on lanthanum oxycarbonate/reduced graphene oxide nanocomposites (CuNi/La2O2CO3/rGO) were successfully fabricated through an impregnation-reduction approach. Well-dispersed and ultrafine CuNi alloy NPs (∼3.2 nm) can be easily anchored onto La2O2CO3/rGO, and the aggregation of metal NPs can be effectively avoided. Benefiting from the small metal NP size, the synergistic effect between Cu and Ni, and the strong metal–support interactions, the Cu0.5Ni0.5/La2O2CO3/rGO nanocomposites (NCs) exhibited remarkably improved catalytic activity and 100% H2 selectively toward N2H4 decomposition, outperforming Cu/La2O2CO3/rGO, Ni/La2O2CO3/rGO, CuNi/rGO, and CuNi/La2O2CO3. The total turnover frequency of Cu0.5Ni0.5/La2O2CO3/rGO catalyst reached up to 114.3 h–1 at 343 K, indicating that the Cu0.5Ni0.5/La2O2CO3/rGO is one of the most active noble-metal-free catalysts ever reported for the same reaction. The low-cost and outstanding catalytic activity of CuNi/La2O2CO3/rGO NCs improved the feasibility of using N2H4·H2O as a chemical hydrogen carrier and is expected to be applied in economic hydrogen-based fuel cells.