Key role of electron accessibility at the noble metal-free catalytic interface in hydrogen evolution reaction

The reactant concentration at the catalytic interface holds the key to the activity of electrocatalytic hydrogen evolution reaction(HER),mainly referring to the capacity of adsorbing hydrogen and electron accessibility.With hydrogen adsorption free energy(ΔGH)as a reactivity descriptor,the volcano curve based on Sabatier principle is established to evaluate the hydrogen evolution activity of catalysts.However,the role of electron as reactant received insufficient attention,especially for noble metal-free compound catalysts with poor conductivity,leading to cognitive gap between electronic conductivity and apparent catalytic activity.Herein we successfully construct a series of catalyst models with gradient conductivities by regulating molybdenum disulfide(MoS_(2))electronic bandgap via a simple solvothermal method.We demonstrate that the conductivity of catalysts greatly affects the overall catalytic activity.We further elucidate the key role of intrinsic conductivity of catalyst towards water electrolysis,mainly concentrating on the electron transport from electrode to catalyst,the electron accumulation process at the catalyst layer,and the charge transfer progress from catalyst to reactant.Theoretical and experimental evidence demonstrates that,with the enhancement in electron accessibility at the catalytic interface,the dominant parameter governing overall HER activity gradually converts from electron accessibility to combination of electron accessibility and hydrogen adsorbing energy.Our results provide the insight from various perspective for developing noble metal-free catalysts in electrocatalysis beyond HER.

High density iridium synergistic sites boosting CO-tolerate performance for PEMFC anode

The usage of cheap crude H2 in proton-exchange membrane fuel cells(PEMFCs)is still unrealistic to date,due to the suffering of the current Pt based nano-catalysts from impurities such as CO in anode.Recently,synergistic active sites between single atom(SA)and nanoparticle(NP)have been found to be promising for overcoming the poisoning problem.However,lengthening the nanoparticle-single atom(SA–NP)interface,i.e.,constructing high density synergistic active sites,remains highly challenging.Herein,we present a new strategy based on molecular fusion strategy to create abundant SA–NP interfaces,with high density SA–NP interfaces created on a two dimensional nitrogen doped carbon nanosheets(Ir-SACs&NPs/NC).Owing to the abundance of SA–NP interface sites,the catalyst was empowered with a high tolerance towards up to 1000ppm CO in H_(2) feed.These findings provide guidelines for the design and construction of active and anti-poisoning catalysts for PEMFC anode.