title: Oxygen reduction electrocatalyst based on strongly coupled cobalt oxide nanocrystals and carbon nanotubes.
abstract: Electrocatalyst for oxygen reduction reaction (ORR) is crucial for a variety of renewable energy applications and energy-intensive industries. The design and synthesis of highly active ORR catalysts with strong durability at low cost is extremely desirable but remains challenging. Here, we used a simple two-step method to synthesize cobalt oxide/carbon nanotube (CNT) strongly coupled hybrid as efficient ORR catalyst by directly growing nanocrystals on oxidized multiwalled CNTs. The mildly oxidized CNTs provided functional groups on the outer walls to nucleate and anchor nanocrystals, while retaining intact inner walls for highly conducting network. Cobalt oxide was in the form of CoO due to a gas-phase annealing step in NH(3). The resulting CoO/nitrogen-doped CNT (NCNT) hybrid showed high ORR current density that outperformed Co(3)O(4)/graphene hybrid and commercial Pt/C catalyst at medium overpotential, mainly through a 4e reduction pathway. The metal oxide/carbon nanotube hybrid was found to be advantageous over the graphene counterpart in terms of active sites and charge transport. Last, the CoO/NCNT hybrid showed high ORR activity and stability under a highly corrosive condition of 10 M NaOH at 80 °C, demonstrating the potential of strongly coupled inorganic/nanocarbon hybrid as a novel catalyst system in oxygen depolarized cathode for chlor-alkali electrolysis.
authors.affiliation: Department of Chemistry,  Stanford University , Stanford, California 94305, United States.
authors.forename: Yongye
authors.initials: Y
authors.lastname: Liang
authors.forename: Hailiang
authors.initials: H
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Diao
authors.forename: Wesley
authors.initials: W
authors.lastname: Chang
authors.forename: Guosong
authors.initials: G
authors.lastname: Hong
authors.forename: Yanguang
authors.initials: Y
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.forename: Liming
authors.initials: L
authors.lastname: Xie
authors.forename: Jigang
authors.initials: J
authors.lastname: Zhou
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Tom Z
authors.initials: TZ
authors.lastname: Regier
authors.forename: Fei
authors.initials: F
authors.lastname: Wei
authors.forename: Hongjie
authors.initials: H
authors.lastname: Dai
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D055664:Electrochemical Techniques; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D037742:Nanotubes, Carbon; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D010087:Oxides; D003035:Cobalt; D010100:Oxygen; C060728:cobalt oxide