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Improved Photoelectrochemical Water Oxidation by the WO3/CuWO4 Composite with a Manganese Phosphate Electrocatalyst

Nam, Ki Min, Cheon, Eun Ah, Shin, Won Jung, Bard, Allen J.
Langmuir 2015 v.31 no.39 pp. 10897-10903
annealing, catalysts, catalytic activity, electric current, electrochemistry, manganese oxides, nanoparticles, oxidation, oxygen production, phosphates, semiconductors, tungsten oxide
We describe a composite of the n-type semiconductors for the photoelectrochemical oxygen evolution reaction (OER). A simple drop-casting technique of mixed precursors and a one-step annealing process were used in the synthesis of the WO₃/CuWO₄ composite. The composite showed improved photocurrent for water oxidation compared to either of the two compounds individually. We discuss possible electron–hole separation mechanisms in two semiconductors comprising a primary photon-absorbing semiconductor of CuWO₄ with a secondary semiconductor of WO₃. When the WO₃/CuWO₄ composite is simultaneously irradiated, the photogenerated hole from the WO₃ valence band transfers to CuWO₄, which results in an enhanced charge separation of CuWO₄. Furthermore, the OER catalytic activity of manganese phosphate (MnPO) was compared to manganese oxide nanoparticles (Mn₂O₃) by electrochemical measurements, showing that the manganese phosphate was more efficient for the OER reaction. To investigate the effect of catalysts on semiconductors, manganese phosphate was deposited on the WO₃/CuWO₄ composite. The result demonstrates the promise of manganese phosphate for improving the photocurrent as well as the stability of the WO₃/CuWO₄ composite.