Anchoring Mo single atoms/clusters and N on edge-rich nanoporous holey graphene as bifunctional air electrode in Zn−air batteries

• Published in: Applied catalysis. B, Environmental Environmental, 2020-11, Vol.276, p.119172, Article 119172
• Main Authors: Du, Peng, Hu, Kailong, Lyu, Juan, Li, Huanglong, Lin, Xi, Xie, Guoqiang, Liu, Xingjun, Ito, Yoshikazu, Qiu, Hua-Jun
• Format: Article
• Language: English
• Subjects: Anchoring; Batteries; Catalysts; Chemical vapor deposition; Co-design; defects/edges; Density functional theory; Dopants; Electrodes; Electrolytes; Graphene; Holey graphene; Metal air batteries; Metals; Nanoparticles; Oxygen evolution reaction; Oxygen reduction reaction; Silicon dioxide; Single-atom Mo; Zinc-oxygen batteries
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119172

[Display omitted] •A 3D nanoporous holey graphene with both N and Mo dopants is prepared.•The edge-rich holey graphene facilitates the doping of pyridinic N and single-atom Mo.•The co-doped nanoporous holey graphene is highly active for ORR and OER. Materials co-design of the single-atom catalytic centers and the supports can push the limits of the emerging wearable metal-air batteries. The metal single-atom catalysts are required to be bifunctional with high efficient electrocatalytic activities for both oxygen reduction and evolution reactions (ORR and OER), and preferably non-noble. The supports, on the other hand, in addition to the requirements of being free-standing, flexible and porous, are required to strongly interact with the metal species to prevent their aggregation. However, satisfying these requirements simultaneously is yet challenging. Here, a free-standing 3D nanoporous holey graphene with both N and single-atom Mo dopants is prepared. The nanoholes are created by chemical vapor deposition method on nanoporous NiMo alloy templates with their surface decorated with catalytically inert SiO2 nanoparticles. The edge-rich graphene induced by the nanoholes facilitates the doping of pyridinic N and single-atom Mo in the fringe near the edges. The resulting N and Mo co-doped nanoporous holey graphene exhibits high bifunctional ORR and OER catalytic activities in alkaline electrolytes. The synergetic effects between N and Mo dopants are also revealed by density functional theory calculations. When incorporated in a solid-state zinc-air battery, the battery is bendable and can be continuously discharged/charged for 88 h with a high power density of 83 mW cm−2. This work provides an efficient route to design metal single atom/cluster doped 3D freestanding nanoporous graphene as flexible electrodes.