Tantalum nitride for photocatalytic water splitting: concept and applications

Abstract

Along with many other solar energy conversion processes, research on photocatalytic water splitting to generate hydrogen and oxygen has experienced rapid major development over the past years. Developing an efficient visible-light-responsive photocatalyst has been one of the targets of such research efforts. In this regard, nitride materials, particularly Ta 3 N 5 , have been the subject of investigation due to their promising properties. This review focuses on the fundamental parameters involved in the photocatalytic processes targeting overall water splitting using Ta 3 N 5 as a model photocatalyst. The discussion primarily focuses on relevant parameters that are involved in photon absorption, exciton separation, carrier diffusion, carrier transport, catalytic efficiency, and mass transfer of the reactants. An overview of collaborative experimental and theoretical approaches to achieve efficient photocatalytic water splitting using Ta 3 N 5 is discussed.

Perovskite Sr1−x Ba x W1−y Ta y (O,N)3: synthesis by thermal ammonolysis and photocatalytic oxygen evolution under visible light

“…It is known that the loaded cobalt oxide particles are mainly in the forms of CoO and Co 3 O 4 [3]. For the calculation, assuming that the molar amount of CoO is the same as that of Co 3 O 4 in the loaded cobalt oxide particles, CoO x was accordingly regarded as Co 2 O 2.5 .…”

“…Artificial photocatalysis for solar water splitting has been regarded as a source for clean and sustainable fuel and chemical production [1][2][3]. To achieve efficient solar energy conversion, it is indispensable that the photon energy in the visible light range should be utilized for the photocatalytic reaction [4].…”

“…In our recent work, we have explored five tungstenbased oxynitride perovskites AW(O,N) 3 , A = Sr, La, Pr, Nd, and Eu as novel materials for visible light-driven photocatalytic water oxidation [12]. Among the five samples, the CoO x -loaded SrW(O,N) 3 exhibited higher photostability and photocatalytic O 2 evolution rate of 3.3 lmol h -1 due to the presence of active sites for O 2 evolution on the surfaces and absence of the intrinsic defects related to the partly filled 4f orbitals.…”

“…For example, the (La,Ca)Ti(O,N) 3 crystals, which were synthesized by thermal ammonolysis of A-site-deficient La 1-x TiO 3.5-3x/2 precursor (x = 0.05) treated in an aqueous solution containing Ca(NO 3 ) 2 Á4H 2 O, showed higher activity for photocatalytic water oxidation (O 2 evolution rate: 40 lmol h -1 ) compared with the pure LaTiO 2 N crystals (O 2 evolution rate: 22 lmol h -1 ) due to their higher crystallinity and lower concentration of intrinsic defects (Ti 3? ) that act as a recombination center for photoexcited electrons and holes [13]. The formation of Ti 3? was restrained by substituting La 3? with Sr 2?…”

“…In the present study, we have synthesized five Ba-and/ or Ta-substituted strontium tungsten oxynitride perovskites Sr 1-x Ba x W 1-y Ta y (O,N) 3 , where x,y = 0,0; 0. 25 Characterization X-ray powder diffraction (XRD) patterns were recorded on a Rigaku MiniflexII X-ray diffractometer (Cu Ka radiation (k = 1.5406 Å )).…”