β-Ni(OH)2/NiS/TiO2 3D flower-like p-n-p heterostructural photocatalysts for high-efficiency removal of soluble anionic dyes and hydrogen releasing

Abstract

An ideal way to have the best of both worlds for environmental protection and energy conservation should be to juggle photocatalytic degrading pollutants and producing hydrogen from the pollutant solution synchronously. Herein, we have designed and synthesized a new 3D flower-like p-n-p heterostructure β-Ni(OH)2/NiS/TiO2 as a photocatalytic device, which is ideally suited for both removal of anionic dye methyl orange (MO), and release of hydrogen from the MO solution driven by photoelectric conversion without the need for using noble metals. The formation structure with optimal molar ratio 0.01-β-Ni(OH)2/0.001-NiS/TiO2 shows superior photocatalytic activity for removal of anionic dye MO and releasing hydrogen, its removal efficiency can reach as high as 98% in 15 min and the production of hydrogen is about 7.2 μmolh−1 from the MO solution. Results and analyses show that the outstanding performances of the sample should be attributed to the synergistic effects on two aspects. One is the high efficient charge separation and transfer driven by the internal electric field at the interfaces of NiS/TiO2 and the exposed high energy {001} facets of TiO2. The other is the modifier β-Ni(OH)2 as an assistant sacrificial agent can play an important role of the holes transfer for charge carriers transport balance in the oxidation-reduction process, and the generated active species NiOOH also has a beneficial effect on degrading MO and releasing hydrogen.