Electrodeposition and Characterization of ZnO Rods Films

Santos, Vanessa Nascimento dos; Machado, Sérgio Antônio Spínola

doi:10.1149/05807.0265ecst

Cited by 1 publication

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“…12b(i)) which is in good agreement with the reported values for electrochemically prepared ZnO nanorods. 38 It is inferred from Fig. 12b(ii) that CoAc deposition does not the alter the flatband potential.…”

Section: Effect Of Concentration Of Comentioning

confidence: 82%

Photochemical Deposition of Co-Ac Catalyst on ZnO Nanorods for Solar Water Oxidation

Irshad

Munichandraiah

2015

J. Electrochem. Soc.

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The preparation of ZnO nanorod films decorated with cobalt-acetate (CoAc) electrocatalyst and its activity for photoelectrolysis of water have been demonstrated. The photochemically prepared CoAc catalyst is chemically and morphologically similar to the electrochemically prepared CoAc catalyst. The on-set potential of oxygen evolution reaction is lower on CoAc-ZnO photoanode in relation to bare ZnO photoanode. There is a three to four fold increase in photooxidation current of OER due to the presence of CoAc co-catalyst on ZnO. Thus, the photochemically prepared CoAc on ZnO is an alternative and efficient co-catalyst for photoelectrochemical oxygen evolution reaction. The enhancement in photocatalytic activity of ZnO by the CoAc catalyst photochemically deposited from acetate buffer solution is significantly greater than the cobalt-phosphate (CoPi) co-catalyst deposited from phosphate buffer solution. Hydrogen is a convenient fuel for the future owing to its high energy density and eco-friendliness.1,2 Currently, around 48 million metric tons of H 2 is produced globally each year mainly from natural gas by steam-methane reforming method. 3,4 As this process leads to the emission of a large amount of CO 2 (240 mega tons per year), it is challenging to develop alternate, clean methods to produce hydrogen. Generation of hydrogen gas from water requires energy of 273 kJ mol −1 . If this energy is available from a renewable energy source such as solar energy, hydrogen can be considered as an economical and green energy source, which is an alternative to fossil fuels.A simple approach is to use photovoltaic cells to power water electrolyzers. However, diurnal variation in the sunlight intensity, a high cost and a low conversion efficiency impede successful commercialization of the present photovoltaic cells. 5 Another approach is to store solar energy directly in the chemical bonds of small molecules, similar to the photosynthesis route adopted by vegetation. A typical example is the photodissociation of water to generate hydrogen fuel. 6 The first report on photodissociation of water into H 2 and O 2 using ntype TiO 2 photoanode and Pt black cathode was reported by Fujishima and Honda 7 in 1972. Following this report, numerous investigations have been reported for photocatalytic and photoelectrochemical water splitting.8 Most of the studies suffer from poor solar to hydrogen conversion efficiency due to fast recombination of photogenerated charge carriers and poor catalytic activity of semiconductor electrodes toward multi-electron oxygen evolution reaction (OER) at the photoanode. 8,9 Several metal oxides such as RuO 2 , 10,11 IrO 2 12,13 etc., are coupled with semiconductor anodes (TiO 2 , ZnO, etc.) as co-catalysts to enhance the sluggish kinetics of water oxidation. However, high cost of Ru and Ir limit their widespread application. Recently, a cobaltphosphate complex (CoPi) are no reports on the photochemical deposition of CoAc catalyst on a n-type semiconductor electrode and its utilization as a co-catalyst i...

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Section: Effect Of Concentration Of Comentioning

confidence: 82%