Unique Ru nanoclusters confined in carbon molecular sieve coatings with tailoring sub-4 Å ultramicropores as a highly efficient and CO-tolerant hydrogen oxidation electrocatalyst

Developing highly efficient and CO-tolerant hydrogen oxidation electrocatalysts is crucial for anion exchange membrane fuel cells (AEMFC). In this work, a unique carbon molecular sieve (CMS) coating strategy is demonstrated for Ru nanoclusters, featuring strongly size sieving ultramicropores, which act as a highly efficient and CO-tolerant hydrogen electrocatalyst in alkaline conditions. The CMS coating thickness and pore size could be regulated by low-temperature carbonization of polydopamine which was beforehand in-situ polymerized over the Ru nanoclusters. It is demonstrated that dominant sub-4 Å ultramicropores in Ru@NC/C-400 are beneficial for H2/CO separation. Taking advantage of such a physical sieving barrier, along with the electronic modulation of Ru by the carbon coating layer, the CO adsorption over the Ru surface is suppressed and meanwhile, the hydrogen/oxygen species adsorption energy is optimized. The Ru@NC/C-400 catalyst exhibits exceptional HOR activity with a specific activity of 0.30 mA cm-2Ru and a mass activity of 0.25 A mg−1 Ru, which are 3-folds and 1.7-folds of the counterpart Pt/C catalyst, respectively. More importantly, the catalyst is highly tolerant to CO. In the presence of 100 ppm CO, the HOR current with the Ru@NC/C-400 catalyst lowers by just 9.5%, but the Pt/C catalyst drops by 33.3% in the chronoamperometry test. This work highlights the tremendous potential of the encapsulating approach in refreshing catalyst performances via rationally engineering the encapsulating layer structures.