Re nanoclusters anchored on nanosheet supports: Formation of Re-O-matrix bonding and evaluation as all-pH-range hydrogen evolution reaction (HER) electrocatalysts

Although the water splitting-based generation of hydrogen as an energy carrier can help to mitigate the global problems of energy shortage and climate change, the practical implementation of this strategy is hindered by the absence of inexpensive high-performance electrocatalysts for the hydrogen evolution reaction (HER). Re-based HER electrocatalysts exhibit predictable high performance within the entire pH range but suffer from arduous formation (i.e., vulnerability to oxidation) and uncontrollable aggregation, which strongly discourages the maximisation of active site exposure required for activity enhancement. To overcome these limitations, we herein hydrothermally synthesise Re nanoclusters uniformly distributed on nanosheet supports, such as reduced graphene oxide nanosheets (Re NCs@rGO), revealing that this hybrid features abundant exposed active sites and high oxidation resistance. The obtained electrocatalysts were elaborately characterized by microscopic and spectroscopic analyses. Also, density functional theory calculations confirm the optimised synthesis of Re NCs@rGO and indicate the crucial role of Re–O–C junction formation in securing durability. The effective suppression of Re nanocluster detachment/dissolution under HER conditions endows Re NCs@rGO with high electron conductivity and electrochemical stability, resulting in a durability superior to that of commercial Pt/C and an activity similar to that of this reference. As a result, Re NCs@rGO exhibited remarkably small HER overpotentials of 110, 130, and 93 mV to deliver a current density of 10 mA cm⁻² in 0.5 M H₂SO₄, 1 M PBS, and 1 M KOH, respectively. Thus, Re NCs@rGO is a promising alternative to conventional Pt-group-metal catalysts and should find applications in next-generation high-performance water splitting systems.