| Semiconductor photocatalysis is considered as one of the effective methods to solve the environmental pollution and energy crisis.Titanium dioxide?Ti O2?has the advantages of high oxidation resistance,low cost,low environmental protection and photochemical stability,and plays an important role in the field of environmental protection.However,the wide band gap of Ti O2,the rapid recombination of photogenerated electron hole pairs which make it unable to use visible light effectively,so the photocatalytic activity and application of Ti O2 are limited.Therefore,in this paper,anatase Ti O2 nanoparticles and carbon quantum dots?CQDs?are compounded to broaden the absorption of the catalyst in the visible light range and inhibit the recombination of photogenerated electrons and holes,so as to improve the photocatalytic performance of Ti O2.A blue fluorescent CQDs solution with oxygen-containing groups and good water solubility was prepared by hydrothermal method at different experimental temperatures.CQDs were characterized by X-ray diffraction,UV-vis and fluorescence.The results show that the main crystalline phase of the CQDs is disordered graphite with oxygen-containing groups on its surface,which has strong absorption in the visible light range and shows photoluminescence behavior depending on the excitation wavelength.CQDs modified anatase Ti O2 composite catalyst material was prepared by hydrothermal method and muffle furnace method,named as 0.1+x-y.The photocatalytic properties of Ti O2/CQDs were evaluated by photocatalytic degradation of methylene blue?MB?and photocatalytic splitting of water for hydrogen production.The mechanism of photocatalysis was analyzed by photoelectric reaction test.The results show that the Ti O2and CQDs are connected by Ti-O,and the photocatalysis activity of the catalyst is improved by enlarging the absorption of the catalyst in the visible light wavelength range,and inhibiting the recombination of photogenerated electrons and holes.The degradation rate of pure Ti O2 is 81.54%,when the adding amount of CQDs at 140°C is 10m L,the degradation rate of MB is 97.64%under UV light.The hydrogen production of pure Ti O2under visible light is zero.When the adding amount of CQDs at 180°C is 10 m L,the hydrogen production rate of is 208.7?mol·h-1·g-1.The hydrogen production rate of the composite was further improved to 412.4?mol·h-1·g-1 by calcining method. |
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