Bimetallic alloy catalysts with optimized metal ratio usually exhibit a superior catalytic hydrogenation activity and selectivity compared to individual mono-metallic catalysts, which has been attributed to the geometric and electronic structure of the alloy in H2 activation. The adsorption properties of small molecules depend on the electronic structure of the surface via i) H2 adsorption, ii) H2 dissociation and iii) H diffusion. The roles of each step in determining the reactivity of catalysts remains unclear. Therefore, an in-depth investigation of the metal-hydrogen stretch would not only provide information on the strength of interaction between hydrogen and metal to help unpack the electronic structure effects, identify the existence of H moieties and unravel the nature of the outstanding activity of the bimetallic catalysts, as well as the role of the catalyst support.