Adsorption and dissociation of borohydride on different Ir-Ni alloy surfaces

Borohydride (BH4−) is considered as one of promising hydrogen storage materials, which could serve as hydrogen source for proton exchange membrane fuel cells (PEMFCs). In this study, the adsorption and dissociation of BH4− on seven Ir-Ni alloy surfaces are investigated by density functional theory (DFT) calculations. Our results indicate that the doping proportion of Ir atoms on these surfaces can affect the adsorption configurations of BH4ad. The 1Ir2Ni-2Ir-Ni(1 1 1) surface (Ni(1 1 1) with surface Ir2Ni and subsurface Ir) has been found as the most beneficial one for the dissociation of BH4ad among these systems. Moreover, the influence of water molecules is discussed. It is found that the binding energies of BH4ad for all systems would decrease by the presence of H2O molecules, due to the reduced charge transfer of B atom and H atoms in BH4ad. In addition, the adsorption of OHad would weaken the effect of H2O molecules for BH4ad hydrolysis on all alloy surfaces. It is expected that our results can provide useful insights for the design and development of Ir-Ni catalysts for borohydride hydrolysis.