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Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency

2018; American Chemical Society; Volume: 3; Issue: 8 Linguagem: Inglês

10.1021/acsenergylett.8b00920

2380-8195

Wen‐Hui Cheng, Matthias H. Richter, Matthias M. May, Jens Ohlmann, David Lackner, Frank Dimroth, Thomas Hannappel, Harry A. Atwater, Hans‐Joachim Lewerenz,

Copper-based nanomaterials and applications

Efficient unassisted solar water splitting, a pathway to storable renewable energy in the form of chemical bonds, requires optimization of a photoelectrochemical device based on photovoltaic tandem heterojunctions. We report a monolithic photocathode device architecture that exhibits significantly reduced surface reflectivity, minimizing parasitic light absorption and reflection losses. A tailored multifunctional crystalline titania interphase layer acts as a corrosion protection layer, with favorable band alignment between the semiconductor conduction band and the energy level for water reduction, facilitating electron transport at the cathode–electrolyte interface. It also provides a favorable substrate for adhesion of high-activity Rh catalyst nanoparticles. Under simulated AM 1.5G irradiation, solar-to-hydrogen efficiencies of 19.3 and 18.5% are obtained in acidic and neutral electrolytes, respectively. The system reaches a value of 0.85 of the theoretical limit for photoelectrochemical water splitting for the energy gap combination employed in the tandem-junction photoelectrode structure.