University of Glasgow

Mark Symes

Leroy Cronin

Jia-Jia Chen

A method is disclosed of manufacturing a semiconductor structure comprising an (001) oriented zincblende structure group III-nitride layer, such as GaN. The layer is formed on a 3C-SiC layer on a silicon substrate. A nucleation layer is formed, recrystallized and then the zincblende structure group III-nitride layer is formed by MOVPE at temperature T3 in the range 750-1000° C., to a thickness of at least 0.5μ. There is also disclosed a corresponding semiconductor structure comprising a zincblende structure group III-nitride layer which, when characterized by XRD, shows that the substantial majority, or all, of the layer is formed of zincblende structure group III-nitride in preference to wurtzite structure group III-nitride. The present invention provides methods for producing hydrogen using a mediator that is capable of reversibly donating and accepting four or more electrons. A method of the invention comprises the steps of reducing a mediator by four or more electrons to yield a reduced mediator, and oxidising a reduced mediator to yield a mediator, and reducing protons to yield hydrogen.

Use of polyoxometalate mediators

The present invention provides methods for producing hydrogen using a mediator that is capable of reversibly donating and accepting four or more electrons. A method of the invention comprises the steps of reducing a mediator by four or more electrons to yield a reduced mediator, and oxidising a reduced mediator to yield a mediator, and reducing protons to yield hydrogen.

The invention provides methods for producing hydrogen and oxygen, comprising the steps of: (i) oxidising a mediator at a working electrode to yield an oxidised mediator, and reducing protons at a counter electrode to yield hydrogen; and (ii) reducing an oxidised mediator at a working electrode to yield a mediator, and oxidising water at a counter electrode to yield oxygen, wherein the oxygen generation step is performed non-simultaneously to the hydrogen generation step, and the oxidised mediator of step (i) is used as the oxidised mediator of step (ii), or the mediator of step (ii) is used as the mediator of step (i), and the mediator has a reversible redox wave lying between the onset of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER).

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Glasgow, United Kingdom

Mark Symes