Single‐atom catalysts (SACs) are attracting widespread interest for the catalytic oxygen reduction reaction (ORR), with Fe−Nx SACs exhibiting the most promising activity. However, Fe‐based catalysts suffer serious stability issues as a result of oxidative corrosion through the Fenton reaction. Herein, using a metal‐organic framework as an anchoring matrix, we for the first time obtained pyrolyzed Cr/N/C SACs for the ORR, where the atomically dispersed Cr is confirmed to have a Cr−N4 coordination structure. The Cr/N/C catalyst exhibits excellent ORR activity with an optimal half‐wave potential of 0.773 V versus RHE. More excitingly, the Fenton reaction is substantially reduced and, thus, the final catalysts show superb stability. The innovative and robust active site for the ORR opens a new possibility to circumvent the stability issue of the non‐noble metal ORR catalysts.

Fuel cell, a sustainable technology that assures a cleaner earth, once experienced disillusion due to the issue of economic viability associated with the massive usage of Pt-based catalysts. To address...

The applications of the most promising Fe-N-C catalysts are prohibited by their limited intrinsic activities. Manipulating the Fe energy level through anchoring electronwithdrawing ligands is found effective in boosting the catalytic performance.However,such regulation remains elusive as the ligands are only uncontrollably introduced oweingt otheir energetically unstable nature.H erein, we report ar ational manipulation strategy for introducing axial bonded Otothe Fe sites,a ttained through hexa-coordinating Fe with oxygen functional groups in the precursor.M oreover,t he Om odifier is stabilized by forming the Fe À O À Fe bridge bond, with the approximation of two FeN 4 sites.The energy level modulation thus created confers the sites with an intrinsic activity that is over 10 times higher than that of the normal FeN 4 site.O ur finding opens an ovel strategy to manage coordination environments at an atomic level for high activity ORR catalysts.

Proton‐exchange membrane fuel cells (PEMFCs) are limited by their extreme sensitivity to trace‐level CO impurities, thus setting a strict requirement for H2 purity and excluding the possibility to directly use cheap crude hydrogen as fuel. Herein, we report a proof‐of‐concept study, in which a novel catalyst comprising both Ir particles and Ir single‐atom sites (IrNP@IrSA‐N‐C) addresses the CO poisoning issue. The Ir single‐atom sites are found not only to be good CO oxidizing sites, but also excel in scavenging the CO molecules adsorbed on Ir particles in close proximity, thereby enabling the Ir particles to reserve partial active sites towards H2 oxidation. The interplay between Ir nanoparticles and Ir single‐atom centers confers the catalyst with both excellent H2 oxidation activity (1.19 W cm−2) and excellent CO electro‐oxidation activity (85 mW cm−2) in PEMFCs; the catalyst also tolerates CO in H2/CO mixture gas at a level that is two times better than that of the current best PtRu/C catalyst.

Lowering the Pt catalyst loading in fuel cell cathodes without sacrificing performance remains a topic of interest. However, achieving such a goal is highly challenging, because lowering the Pt loading not only reduces the overall kinetics of the oxygen reduction reaction but also causes a serious mass-transfer issue in the high-current density domain (HCD). Herein, we overcome this difficulty by obtaining a highly active and stable Pt cluster-based catalyst, where the decrease in loading is completely compensated by the extraordinarily high electrochemical specific area and high dispersion of the platinum clusters. The Pt clusters, with average size of 1.3 ± 0.4 nm and atomic utilization rate up to 32.81%, are highly stabilized because of the strong anchoring effect of the N,P-doped carbon nanosheets. The final Pt-9.3@NPC catalyst outcompetes commercial Pt/C catalyst in terms of activity and stability during potential cycling. In addition, the cell assembled by Pt-9.3@NPC as cathode (0.05 mgPt cm–2) conveys much higher performance (1071 mW cm–2) in H2/air mode than the counterpart commercial catalysts (853 mW cm–2, 0.1 mgPt cm–2) and much lower voltage loss at the HCD, clearly evidencing the success in surmounting the mass-transfer problem.

Selectively pyridinic and pyrrolic nitrogen doped porous carbon was synthesized and acted as an excellent electrocatalyst for the ORR.

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Single-atom catalysts (SACs) are attracting widespread interest for the catalytic oxygen reduction reaction (ORR), with FeÀN x SACs exhibiting the most promising activity.H owever,F e-based catalysts suffer serious stability issues as ar esult of oxidative corrosion through the Fenton reaction. Herein, using am etal-organic framework as an anchoring matrix, we for the first time obtained pyrolyzed Cr/ N/C SACs for the ORR, where the atomically dispersed Cr is confirmed to have aCrÀN 4 coordination structure.The Cr/N/C catalyst exhibits excellent ORR activity with an optimal halfwave potential of 0.773 Vv ersus RHE. More excitingly,t he Fenton reaction is substantially reduced and, thus,t he final catalysts show superb stability.T he innovative and robust active site for the ORR opens an ew possibility to circumvent the stability issue of the non-noble metal ORR catalysts.