A strongly coupled Ru-CrO_x cluster-cluster heterostructure for efficient alkaline hydrogen electrocatalysis

Constructing well-defined heterostructure interfaces in catalysts is an efficient strategy to break the so-called scaling relationships and to accelerate the reactions involving multiple intermediates. Here a cluster-cluster heterostructure catalyst composed of crystalline ruthenium cluster and amorphous chromium oxide cluster is designed to realize high-performance alkaline hydrogen electrocatalysis. The strongly coupled cluster-cluster heterostructure interface induces a unique interfacial interpenetration effect, which simultaneously optimizes the adsorption of intermediates on each cluster. The resulting catalyst exhibits impressive catalytic activities for the hydrogen oxidation reaction (exchange current density of 2.8 A mg-1Ru) and the hydrogen evolution reaction (mass activity of 23.0 A mg(-1)Ru at the overpotential of 100 mV) in alkaline media. The hydroxide exchange membrane fuel cell delivers a mass activity of 22.4 A mg(-1)Ru at 0.65 V and outstanding durability with no voltage loss over 105 h operation at 500 mA cm(-2). The present work demonstrates the superiority of cluster-cluster heterostructure interface towards the development of advanced catalysts.