

To radically address such issues, an ideal alkaline HOR electrocatalyst (e.g., platinum group metal (PGM)-based and Ni-based) should feature the following attributes: (1) in addition to the main active sites, another type of active site with selective adsorption-desorption behavior for specific reactant species should be deployed on the electrocatalyst surface to essentially avoid the mutual adsorption-desorption competition between reactant species 5, 24, 25, 26 (2) the dissimilar active sites should be well distributed in the electrocatalyst at the atomic level and have synergistic effects with the main active sites to promote the interfacial HOR kinetics and resist CO poisoning via regulating the d-band centers, and concurrently strengthen the structural stability of the electrocatalyst 7, 8, 17, 27, 28 (3) the electrocatalyst should have an ultrasmall size to maximumly uplift its atomic utilization 29, 30, 31, 32.

Although previous researches have improved the alkaline HOR performance of Pt electrocatalysts by decreasing the size or engineering the composition/structure with other metals to conserve the Pt dosage, and regulating the d-band center to adjust the adsorption-desorption behavior of *H, *OH, and CO species, they failed to fundamentally solve the mutual competition issues of such reactant species on the active sites of Pt electrocatalysts 11, 23. Therefore, designing high-performance Pt electrocatalysts with low Pt dosage and high durability is extremely desirable for alkaline HOR, which should be the stone of killing two birds (i.e., low abundance of Pt element and unsatisfactory alkaline HOR performance).īy deciphering the alkaline HOR process 2, 17, 18, 19, it is found that the mutual competition in the adsorption-desorption between reaction intermediates (e.g., *H and *OH) and CO on the surface-active sites of electrocatalysts is the key reason for the low catalytic activity and poor CO tolerance 20, 21, 22. However, the large-scale implementation of conventional Pt/C electrocatalysts in alkaline HOR catalysis is beset by ultralow catalytic efficiency (e.g., two orders of magnitude decline), extortionate Pt dosage (e.g., ten times higher than that in acidic media), and poor durability in terms of weak CO tolerance and feeble stability 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. Hydrogen fuel cells as green yet high-efficiency energy suppliers are very attractive in contributing to fulfilling carbon neutrality, which is greatly benefited from the deployment of precious Pt electrocatalysts performing best in catalyzing anodic hydrogen oxidation reaction (HOR) due to the optimal adsorption/desorption energy toward hydrogen intermediates 1, 2, 3. This work may shed light on the design of metal nanocluster-based electrocatalysts for energy conversion.


Mechanism studies reveal that oxophilic single-atom lanthanide species in Pt nanoclusters can serve as the Lewis acid site for selective OH - adsorption and regulate the binding strength of intermediates on Pt sites, which promotes the kinetics of hydrogen oxidation and CO oxidation by accelerating the combination of OH − and *H/*CO in kinetics and thermodynamics, endowing the electrocatalyst with up to 14.3-times higher mass activity than commercial Pt/C and enhanced CO tolerance. Herein we report the design of a series of single-atom lanthanide (La, Ce, Pr, Nd, and Lu)-embedded ultrasmall Pt nanoclusters for efficient alkaline hydrogen electro-oxidation catalysis based on vapor filling and spatially confined reduction/growth of metal species. Designing Pt-based electrocatalysts with high catalytic activity and CO tolerance is challenging but extremely desirable for alkaline hydrogen oxidation reaction.
