This review summarizes the recent progress on metallic Ru-based catalysts, including the preparation strategies, performance of electrocatalytic and photocatalytic hydrogen evolution.

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As the best electrocatalysts for alcohol oxidation reactions in direct alcohol fuel cells (DAFCs), Pt-based nanomaterials still face the challenges of low utilization efficiency of Pt atoms and poor reaction kinetics. To address these issues, a self-etching strategy is developed to prepare PtBi nanorings (NRs) with abundant low-coordinated atoms and inhomogeneous tensile strain (≈4%). The obtained PtBi NRs exhibit superior activity toward methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) in alkaline media. Particularly, the mass activities of PtBi NRs for MOR and EOR are 9.4 and 8.5 times higher than those of commercial Pt/C, respectively, which are among the best in the reported Pt-based catalysts. The highly open structure of PtBi NRs is believed to provide plentiful catalytic active sites and increase the utilization of Pt atoms. Theoretical calculations show that the two important factors, i.e., adsorption energy with the key reaction intermediates and the energy barrier for the potential-determining step, are significantly optimized owing to the synergy of tensile strain and the ligand effect in PtBi NRs. This study offers a promising strategy for the rational design and preparation of highly efficient catalysts for DAFCs.

Ordered intermetallic nanomaterials with a well‐defined crystal structure and fixed stoichiometry facilitate the predictable control of their electronic structure and catalytic performance. To obtain the thermodynamically stable intermetallic structures, the conventional approaches with high‐temperature annealing are still far from satisfactory, because of annealing‐induced aggregation and sintering of nanomaterials. Herein, a general wet‐chemical method is developed to synthesize a series of noble metal–based intermetallic nanocrystals, including hexagonal close‐packed (hcp) PtBi nanoplates, face‐centered cubic (fcc) Pd3Pb nanocubes, and hcp Pd2.5Bi1.5 nanoparticles. During the synthetic process, Br− ions play two important roles for the formation of ordered intermetallic structures: i) Br− ions can coordinate with the metal ions to decrease their reduction potentials thus slowing down the reduction kinetics. ii) Br− ions can combine with molecular oxygen to generate an oxidative etching effect, hence reconstructing the atom arrangement, which is beneficial for the formation of the intermetallic structure. As a proof‐of‐concept application, Pd3Pb nanocubes are used as electrocatalysts for ethanol and methanol oxidation reactions, which exhibit significantly improved electrochemical performance compared with the commercial Pd black catalyst.

Benefiting from ordered atomic structures and strong d‐orbital interactions, intermetallic compounds (IMCs) are promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, the body‐centered cubic IrGa IMCs with atomic donor–acceptor architectures are synthesized and anchored on the nitrogen‐doped reduced graphene oxide (i.e., IrGa/N‐rGO). Structural characterizations and theoretical calculations reveal that the electron‐rich Ir sites are atomically dispersed in IrGa/N‐rGO, facilitating the electron transfer between Ir atoms and adsorbed species, which can efficiently decrease the energy barriers of the potential determining step for both HER and OER. Impressively, the IrGa/N‐rGO||IrGa/N‐rGO exhibits excellent performance for overall water splitting in alkaline medium, requiring a low cell voltage of 1.51 V to achieve 10 mA cm−2, meanwhile, exhibiting no significant degradation for 100 h. This work demonstrates that the rational design of noble metal electrocatalysts with donor–acceptor architectures is beneficial for catalytic reactions in energy conversion applications.