GaN:ZnO Solid Solution as a Photocatalyst for Visible-Light-Driven Overall Water Splitting

Abstract

Photocatalytic overall water splitting has been studied extensively from the viewpoint of solar energy conversion. Despite numerous attempts, none have yielded satisfactory results for the development of photocatalysts, which work under visible light irradiation to efficiently utilize solar energy. We report here the first example of visible-light-driven overall water splitting on a novel oxynitride photocatalyst, a solid solution of GaN and ZnO with a band gap of 2.58-2.76 eV, modified with RuO2 nanoparticles. In contrast to the conventional non-oxide photocatalysts, such as CdS, the solid solution is stable during the overall water splitting reaction. This is the first example of achieving overall water splitting by a photocatalyst with a band gap in the visible light region, which opens the possibility of new non-oxide-type photocatalysts for energy conversion.

Chemical trends of stability and band alignment of lattice-matched II-VI/III-V semiconductor interfaces

“…It has been proposed that mixing lattice-match II-VI with III-V semiconductors could be an efficient way to tune the material properties for specific applications [1][2][3][4][5][6][7] because the II-VI and III-V usually has much larger tunability than isovalent semiconductor alloys [e.g., the band gap of GaAs (1.5 eV) is much smaller than that of ZnSe (2.8 eV), even though they are lattice-matched, see Table I]. For example, lattice-matched ZnO/GaN alloys have been suggested as a good candidate of electrode for high efficiency solar hydrogen production through photoelectrochemical water splitting 3,8,9 ; lattice-matched ZnSe/GaAs and ZnTe/GaSb heterojunctions are proposed to be high quality blue-green emitters 10,11 .…”

“…For example, lattice-matched ZnO/GaN alloys have been suggested as a good candidate of electrode for high efficiency solar hydrogen production through photoelectrochemical water splitting 3,8,9 ; lattice-matched ZnSe/GaAs and ZnTe/GaSb heterojunctions are proposed to be high quality blue-green emitters 10,11 . ZnTe/GaSb have also been proposed as good candidate for tandem solar cell absorbers materials because GaSb has a band gap of 0.8 eV and ZnTe has a band gap of 2.4 eV, therefore, their alloys and superlattices can cover a large range of solar spectrum without significant change in the lattice constant 7 .…”

Temperature and composition dependence of short-range order and entropy, and statistics of bond length: the semiconductor alloy (GaN)1−x(ZnO)x

“…The pseudobinary (GaN) 1−x (ZnO) x semiconductor alloy is promising as a photocatalyst using visible light for splitting water into O 2 and protons [1] [2]. A co-catalyst (e.g.…”

Formation of Layered Bi5Ti3FeO15Perovskite in Bi2O3-TiO2-Fe2O3Containing System

“…To date, several research groups have developed visible active photocatalysts of oxide, sulfide, oxynitride such as PbBi2Nb2O9, (Ga1-xZnx)(N1-xOx), Zr-S co-doped TiO2, NixIn1-xTaO4, TaON, TiO2-xNx, TiO2-xCx, and AgGa1-x InxS2, etc. [1][2][3][4][5][6][7][8][9] In search of the highly efficient photocatalysts under visible light irradiation, we have recently discovered a novel single oxide photocatalysts, PbBi2Nb2O9, with an Aurivillius-phase perovskite as well as nanocomposite and p-n junction nanodiode, etc. [10][11][12][13][14] But, we still need highly efficient, small band gap (ca.…”