This study investigates the feasibility of using a mixed phase manganese dioxide (MnO2) in the graphite supported Pt catalyst layer to perform a light-driven photoelectrochemical cell. The effects of the conditions of preparing a mixed phase MnO2 on their properties are evaluated. By adjusting the precursor concentrations down to 0.1 M, the multi-diffraction peaks of alpha-, beta-, epsilon- and gamma-MnO2 can be obtained and shown to display strong vibrational bands related to the pyrolusite and ramsdellite structure. In particular, a significant enhancement on the photodegradation test has been observed with an optimum degradation efficiency ratio (monomeric/dimeric) of 1.089. Furthermore, by adding a mixed phase MnO2 in the catalyst layer, the electrode shows the related hydrophilic surface characteristics, and the advancing contact angle, receding contact angle and contact angle decrease to 121.91 degrees, 117.77 degrees and 106.64 degrees, respectively. After light illumination, a significant light-induced hydrogen generation by CH3OH aqueous solution splitting is observed. The incorporation of mixed phase MnO2 within graphite supported Pt catalyst layer largely enhances the photoelectrochemical cell performance from 2.18 mW cm(-2) to 2.92 mW cm(-2). (C) 2014 The Electrochemical Society. All rights reserved.