Adaptive Catalytic Nanointerfaces for Controlled Hydrogen Evolution: an in Situ Electrochemical Approach.

Precious metal nanoparticles in electrocatalytic applications tend to be single-use, becoming unusable afterward. Here, this is demonstrated that the electrocatalytic response of these nanoparticles, when confined at the step-edges of corrugated carbon nanofibers interiors, can be switched on again at will by simply introducing sulfur as an inorganic mediator. To achieve this, an electrochemical methodology is developed that triggers the rapid surface reconfiguration of confined, deactivated nanoparticles (PdS) involving the release of sulfur to yield highly active crystalline Pd(0) nanoparticles, confined polysulfides, and sulfur-terminated carbon step-edges. More importantly, the electrochemical performance can be systematically switched from a highly active mode, in which polysulfides enhance the hydrogen adsorption on palladium, to a much less active mode, called the resting mode, in which sulfur (formed by the oxidation of polysulfides) passivates the active Pd(0) nanoparticle surface. This discovery introduces a new protocol to control nanoparticle performance for catalytic reactions, and more crucially, to extend their lifespan.