title: Catalytic Activity and Impedance Behavior of Screen-Printed Nickel Oxide as Efficient Water Oxidation Catalysts.
abstract: We report that films screen printed from nickel oxide (NiO) nanoparticles and microballs are efficient electrocatalysts for water oxidation under near-neutral and alkaline conditions. Investigations of the composition and structure of the screen-printed films by X-ray diffraction, X-ray absorption spectroscopy, and scanning electron microscopy confirmed that the material was present as the cubic NiO phase. Comparison of the catalytic activity of the microball films to that of films fabricated by using NiO nanoparticles, under similar experimental conditions, revealed that the microball films outperform nanoparticle films of similar thickness owing to a more porous structure and higher surface area. A thinner, less-resistive NiO nanoparticle film, however, was found to have higher activity per Ni atom. Anodization in borate buffer significantly improved the activity of all three films. X-ray photoelectron spectroscopy showed that during anodization, a mixed nickel oxyhydroxide phase formed on the surface of all films, which could account for the improved activity. Impedance spectroscopy revealed that surface traps contribute significantly to the resistance of the NiO films. On anodization, the trap state resistance of all films was reduced, which led to significant improvements in activity. In 1.00 m NaOH, both the microball and nanoparticle films exhibit high long-term stability and produce a stable current density of approximately 30 mA cm(-2) at 600 mV overpotential.
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia. archanas002@gmail.com.|Australian Centre of Excellence for Electromaterials Science, Monash University, Victoria, 3800, Australia. archanas002@gmail.com.|Advanced Materials and Processing Research Institute, CSIR, Bhopal, India. archanas002@gmail.com.
authors.forename: Archana
authors.initials: A
authors.lastname: Singh
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia.|Australian Centre of Excellence for Electromaterials Science, Monash University, Victoria, 3800, Australia.
authors.forename: Monika
authors.initials: M
authors.lastname: Fekete
authors.affiliation: Manufacturing Flagship, CSIRO, Clayton, Victoria, 3168, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gengenbach
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia.|Australian Centre of Excellence for Electromaterials Science, Monash University, Victoria, 3800, Australia.
authors.forename: Alexandr N
authors.initials: AN
authors.lastname: Simonov
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia.|Australian Centre of Excellence for Electromaterials Science, Monash University, Victoria, 3800, Australia.|School of Chemistry, James Cook University, Townsville, Queensland, 4811, Australia.
authors.forename: Rosalie K
authors.initials: RK
authors.lastname: Hocking
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia.
authors.forename: Shery L Y
authors.initials: SL
authors.lastname: Chang
authors.affiliation: Department of Materials Science and Engineering, Monash University, Victoria, 3800, Australia.
authors.forename: Mathias
authors.initials: M
authors.lastname: Rothmann
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia.
authors.forename: Satvasheel
authors.initials: S
authors.lastname: Powar
authors.affiliation: Department of Materials Science and Engineering, Monash University, Victoria, 3800, Australia.
authors.forename: Dongchuan
authors.initials: D
authors.lastname: Fu
authors.affiliation: Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, PR China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Materials Science and Engineering, Monash University, Victoria, 3800, Australia.|Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, PR China.
authors.forename: Yi-Bing
authors.initials: YB
authors.lastname: Cheng
authors.affiliation: Manufacturing Flagship, CSIRO, Clayton, Victoria, 3168, Australia.|Department of Materials Science and Engineering, Monash University, Victoria, 3800, Australia.|Melbourne Centre for Nanofabrication, Clayton, Victoria, 3168, Australia.
authors.forename: Udo
authors.initials: U
authors.lastname: Bach
authors.affiliation: School of Chemistry, Monash University, Victoria, 3800, Australia. leone.spiccia@monash.edu.|Australian Centre of Excellence for Electromaterials Science, Monash University, Victoria, 3800, Australia. leone.spiccia@monash.edu.
authors.forename: Leone
authors.initials: L
authors.lastname: Spiccia
mesh_terms: D002384:Catalysis; D017097:Electric Impedance; D053758:Nanoparticles / Q000737:chemistry; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D011327:Printing; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D009532:Nickel; C028007:nickel monoxide
keywords: nanostructures; nickel oxide; screen printing; thin films; water oxidation catalysis