Synergetic coupling of Pd nanoparticles and amorphous MoSx toward highly efficient electrocatalytic hydrogen evolution reactions

Abstract Noble metal palladium (Pd) has been widely used in hydrogen-related catalytic reactions. However, its performances toward hydrogen evolution reactions (HER) are intrinsically restricted due to a strong bonding of Pd–H thus make the hydrogen desorption difficult. In this work, being as an electron–cocatalyst, Pd nanoparticles are anchored on our well-established amorphous MoS x /TiO 2 nanotube arrays (TNAs) electrocatalyst system through an electrochemical deposition technique. The unique electronic structure in the S-vacancies and/or unsaturated S atoms of MoS x significantly weaken the Pd–H bonding in the electrocatalytic process, facilitating the hydrogen desorption process. In the meantime, conductivity of MoS x /TNAs is largely improved due to incorporation of Pd nanoparticles into the system, which enables the charge transfer from electrode to active site of MoS x more efficient. The synergetic coupling of Pd and MoS x /TNAs result in a superior electrocatalytic activity, achieving an onset overpotential of −29 mV, overpotentials of −64 and −88 mV at −10 and −20 mA cm −2 , which are equivalent to that from Pt catalysts.