Recycling Spent LiCoO_(2)Battery as a High-efficient Lithiumdoped Graphitic Carbon Nitride/Co_(3)O_(4)Composite Photocatalyst and Its Synergistic Photocatalytic Mechanism

The ever-increasing quantity of spent lithium-ion batteries(LIBs)is both a potential environmental pollutant and a valuable resource.The spent LIBs recycling mainly aimed at the separation of valuable elements.Some issues still exist in these processes such as high energy consumption and complex separation procedures.This study avoided element separation and proposed a facile approach to transform spent LiCoO_(2) electrode into a lithium(Li)-doped graphitic carbon nitride(g-C_(3)N_(4))/Co_(3)O_(4) composite photocatalyst through one-pot in situ thermal reduction.During the thermal process,melamine served as the reductant for LiCoO_(2) decomposition and the raw material for g-C_(3)N_(4) production.Li was in situ doped in g-C_(3)N_(4) and the generated Co_(3)O_(4) was in situ integrated,forming a Li-doped g-C_(3)N_(4)/Co_(3)O_(4) composite photocatalyst.This special composite exhibited an enhanced photocatalytic performance,and its photocatalytic H2 production and RhB degradation rates were 8.7 and 6.8 times higher than those of g-C_(3)N_(4).The experiments combined with DFT calculation revealed that such enhanced photocatalytic efficiency was ascribed to the synergy effect of Li doping and Co_(3)O_(4) integrating,which extended the visible light absorption(450-900 nm)and facilitated the charge transfer and separation.This study transforms waste into a high-efficient catalyst,realizing high-valued utilization of waste and environmental protection.

Synthesis of AgCl/Ti_(3)C_(2)@TiO_(2)Ternary Composite Photocatalysts for Photocatalytic Oxidation of 1,4-Dihydropyridine and Tetracycline Hydrochloride

AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.

Photodecomposition of H_2S to H_2 over Cd_xZn_(1-x)S composite photocatalysts

A series of CdxZn1-xS (x = 0.1-0.9) photocatalysts were prepared by coprecipitation. They could form solid solution semiconductors with hexagonal phase in agreement with pure CdS by characterization of XRD. The photophysical properties of CdxZn1-xS photocatalysts were measured by UV-Vis diffuse reflectance spectrum and surface photovoltage spectroscopy (SPS). The band gap energy gradually reduced with the increasing of x value in CdxZn1-xS,and when x = 0.7,the Cd0.7Zn0.3S photocatalyst had the strongest surface photovoltage. CdxZn1-xS photocatalysts were used in the photodecomposition of H2S to H2. The evolution rate of H2 over the Cd0.7Zn0.3S photocatalyst was also the highest among CdxZn1-xS photocatalysts. And the effect of calcination temperature on the evolution rate of H2 was investigated and the optimum temperature was 650°C.

Heterojunction： important strategy for constructing composite photocatalysts

As an ideal solution to energy and environment issues,conversion of sunlight into solar fuels by photocatalytic water splitting and greenhouse gas(CO_2)reduction has attracted keen research interest of multi-field scientists.In the past four decades,a large number of semiconductor photocatalysts have been

Preparation and characterization of Fe_(2)O_(3)/Bi_(2)WO_(6)composite and photocatalytic degradation mechanism of microcystin-LR

The long-standing popularity of semiconductor photocatalysis,due to its great potential in a variety of applications,has resulted in the creation of numerous semiconductor photocatalysts,and it stimulated the development of various characterization methods.In this study,Fe_(2)O_(3)/Bi_(2)WO_(6)composite with a flower-like microsphere and hierarchical structure was synthesized with the facile hydrothermal-impregnation method without any surfactants.X-ray diffraction(XRD),scanning electron microscopy(SEM),ultravioletevisible(UV-Vis)diffuse reflectance spectroscopy,and photoluminescence spectroscopy were used to characterize the structures of the samples.The specific surface area was estimated with the Brunauer-Emmett-Teller(BET)method,and pore size distribution was determined using the Barrett-Joyner-Halenda(BJH)method.The synthesized Fe_(2)O_(3)/Bi_(2)WO_(6)composite had an average diameter of approximately 4 nm,with smaller specific surface area and larger pore diameter than those of pristine Bi_(2)WO_(6).The results of XRD and SEM analyses confirmed that the composite was composed of Fe_(2)O_(3)and Bi_(2)WO_(6).The absorption edge of Bi_(2)WO_(6)was at a wavelength of 460 nm.By contrast,the absorption edge of Fe_(2)O_(3)/Bi_(2)WO_(6)to visible light was redshifted to 520 nm,with narrower bandgap width and stronger visible light response.It was also found that the main active substances in the degradation of microcystin-LR(MC-LR)were hydroxyl radicals(·OH)and electron holes(h^(+)).Consequently,the results further showed that the heterojunction between Fe_(2)O_(3)and Bi_(2)WO_(6)can improve the charge transfer rate and effectively separate the photoinduced electrons and holes.Compared with Bi_(2)WO_(6),Fe_(2)O_(3)/Bi_(2)WO_(6)had no significant difference in the adsorption capacity of MC-LR and had more efficient photocatalytic degradation activity of MC-LR.The degradation rates of MC-LR by Fe_(2)O_(3)/Bi_(2)WO_(6)and Bi_(2)WO_(6)reached 80%and 56%,respectively.The degradation efficiency of MC-LR was affected by the initial pH value,initial Fe_(2)O_(3)/Bi_(2)WO_(6)concentration,and initial MC-LR concentration.