2015 AIChE Annual Meeting Proceedings

(66b) Electrodeposition of a MnOx Catalytic Film By Multi-Session Cyclic Voltammetry and Assessment for Water Oxidation

Authors

Yuan, H. - Presenter, Michigan State University
Ofoli, R. - Presenter, Michigan State University

Abstract

Electrodeposition of a MnOx catalytic film by multi-session cyclic voltammetry and assessment for water oxidation

For AIChE National Meeting in Salt Lake City, UT

Hao Yuan (yuanhao@msu.edu) and Robert Y. Ofoli

Michigan State University, East Lansing 48824

Stable and effective catalysts are key to hydrogen production through water splitting. We have recently developed a new method to synthesize an inexpensive MnOx catalytic film in situ on FTO in aqueous media. This approach uses a simple electrodeposition protocol involving two cyclic voltammetry (CV) sessions over two different ranges of potential (0.0 to 0.6 V and 0.6 to 2.0 V), followed by calcination. The resulting film has a fibrous nanoscale morphology that is uniformly distributed on the conductive surface. Its surface morphology and elemental composition were characterized by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The catalytic functionality was assessed by cyclic voltammetry, which showed an onset potential of ~1.0V vs. Ag/AgCl and excellent effectiveness towards water oxidation. It successfully enabled the water splitting reaction with a platinum wire or a Ni/NiO catalyst which is also electrodeposited by cyclic voltammetry in a simple device powered by a single AA alkaline battery. Its stability was assessed by consecutive CV and long term amperometry experiments, with the results showing stable catalytic performance over long periods of time. A nucleation-growth theory is proposed to explain the mechanism for the formation of the fibrous surface morphology, and has been supported by SEM, XRD and XPS assessments. The effects of other synthesis conditions such as ionic strength, potential ranges, and number of scanning cycles were also evaluated. Efforts on integrating the catalyst with a solar collector and a hydrogen evolving catalyst to build an inexpensive, highly effective water splitting device have so far shown promising results.