Bimetallic NiIr nanoparticles supported on lanthanum oxy-carbonate as highly efficient catalysts for hydrogen evolution from hydrazine borane and hydrazine

Recently, the utilization of hydrazine borane (N2H4BH3) and hydrous hydrazine (N2H4 center dot H2O) as promising hydrogen carriers has received increasing research interest. In this work, NiIr alloy nanoparticles (NPs) immobilized on lanthanum oxy-carbonate (NiIr/La2O2CO3) have been successfully synthesized through a sodium-hydroxide-assisted reduction approach at room temperature. It was found that ultrafine NiIr NPs with an average size of around 2.3 nm were effectively and highly dispersed on La2O2CO3. NiIr/La2O2CO3 nanocomposites (NCs) prepared with the assistance of NaOH showed much higher catalytic activity and H2 selectivity toward the N2H4BH3 dehydrogenation reaction as compared to those of NiIr/La2O2CO3-N prepared without addition of NaOH. Among all of the tested samples, the optimized Ni0.75Ir0.25/La2O2CO3 NCs exhibited the highest catalytic performance with 100% hydrogen selectivity for hydrogen generation from an aqueous solution of N2H4BH3. The total turnover frequency (TOF) of Ni0.75Ir0.25/La2O2CO3 NCs for this dehydrogenation reaction was found to be 1250 h(-1) at 323 K, which is among the highest values ever reported. Additionally, this catalyst also exhibited a remarkable catalytic performance for efficient and complete decomposition of N2H4 center dot H2O. This excellent catalytic performance could be attributed to the high dispersion of metal NPs and the strong interaction between the metal and support as well as the promotion effect of NaOH.