In situ growth of cobalt on ultrathin Ti_(3)C_(2)T_(x)as an efficient cocatalyst of g-C_(3)N_(4)for enhanced photocatalytic CO_(2)reduction

Photocatalytic CO_(2)reduction to valuable product exhibit promising prospect for solving the energy crisis and the greenhouse effect.Herein,Co-Ti_(3)C_(2)T_(x)/g-C_(3)N_(4)(Co-TC/CN)composite with enhanced photocatalytic performance for converting CO_(2)to CO and CH_(4)was constructed by electrostatic self-assembly method.The close contact interface between Co-Ti_(3)C_(2)T_(x)and g-C_(3)N_(4)nanosheets can be used as fast transport channels of photogenerated electrons and effectively promote the separation of photogenerated electrons and holes,and the interface between the Co and Ti_(3)C_(2)T_(x)might be the active sites for CO_(2)adsorption and activation.The optimized Co-Ti_(3)C_(2)T_(x)/g-C_(3)N_(4)composite exhibited the highest photocatalytic performance with the CO and CH_(4)production of 55.04 μmol·g^(-1)and 2.29 μmol·g^(-1),respectively,which were 7.5 times and 5.8 times than those of g-C_(3)N_(4).Furthermore,the stability of g-C_(3)N_(4)was improved after coupling with Co-Ti_(3)C_(2)T_(x).

光催化CO_(2)还原的超薄层状催化剂

随着工业化进程加快和消费结构的持续升级,大气中CO_(2)的含量远超过去水平,成为了一个严重的全球性环境问题。光催化CO_(2)还原是解决大气中二氧化碳含量上升的最有前景的手段之一,该技术的核心是开发高效、环保、廉价的光催化剂。凭借大比表面积、大量低配位表面原子,从催化剂内部到表面转移距离更短等性能优势,超薄层状材料显示出实现光催化二氧化碳还原的巨大潜力。本文总结了用于光催化CO_(2)还原的超薄层状光催化剂的最新进展,对现有催化剂进行了分类,对其制备方法和光催化CO_(2)还原机理进行了介绍。另外,重点对保持超薄催化剂层状结构的前提下,采用厚度调整、掺杂、构造缺陷和复合等改进催化剂光催化性能的策略进行了讨论。最后,对用于光催化二氧化碳还原的超薄层状光催化剂的未来机遇和挑战进行了展望。

Preparation of Ni/bentonite catalyst and its applications in the catalytic hydrogenation of nitrobenzene to aniline

Ni supported on bentonite was prepared by the impregnation method with different nickel contents, applied to the hydrogenation of nitrobenzene to aniline in a fixed-bed reactor, and it was characterized by X-ray diffraction(XRD), H_2-temperature programmed reduction(H_2-TPR), and X-ray photoelectron spectrometry(XPS). The results showed that Ni/bentonite catalyst with 20 wt% nickel content provided a higher conversion of nitrobenzene and selectivity of aniline compared to other catalysts. Ni O was the precursor of the active component of the catalyst, and the small crystallite size as well as the highly dispersed Ni O on the Ni/bentonite-20 catalyst, contributed to the catalytic performance. The hydrogenation of nitrobenzene was carried out at 300 °C with a H_2 gaseous hourly space velocity of 4800 ml·(g cat)^(-1)·h^(-1)and a nitrobenzene liquid hourly space velocity of4.8 ml·(g cat)^(-1)·h^(-1)over Ni/bentonite-20. A 95.7% nitrobenzene conversion and 98.8% aniline selectivity were obtained. While the nitrobenzene liquid hourly space velocity was 4.8 ml·(g cat)^(-1)·h^(-1), the yield of aniline was more than 95.0% during a 10-hour reaction.

Ni/bentonite catalysts prepared by solution combustion method for CO_2 methanation

A 20 wt% Ni/bentonite catalyst was prepared by a solution combustion synthesis (SCS), which exhibited higher activity for the CO_2methanation than that of an impregnation method (IPM), and the catalyst prepared by SCS showed a CO_2 conversion of 85% and a CH4selectivity of 100% at 300 °C, atmospheric pressure, and 3600 ml·(g cat)-1·h-1, and the catalyst exhibited stable within a 110-h reaction. The results showed higher me- tallic Ni dispersion, smaller Ni particle size, larger specific surface area and lower reduction temperature in the Ni/ bentonite prepared by SCS than that of IPM. And the Ni/bentonite prepared by the SCS moderated the interaction between NiO and bentonite.

Mechanically activated starch magnetic microspheres for Cd(Ⅱ)adsorption from aqueous solution

Magnetic starch microspheres(AAM-MSM)were synthesized via an inverse emulsion graft copolymerization by using mechanically activated cassava starch(MS)as a crude material,acrylic acid(AA)and acrylamide(AM)as graft copolymer monomers,and methyl methacrylate(MMA)as the dispersing agent and used as an adsorbent for the removal of Cd(Ⅱ)ions from aqueous solution.Fourier-transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and vibrating sample magnetometry(VSM)were used to characterize the AAM-MSM adsorbent.The results indicated that AA,AM,and MMA were grafted to the MS,and the Fe_(3)O_(4) nanoparticles were encapsulated in the AAM-MSM adsorbent microspheres.The adsorbent exhibited a smooth surface,uniform size,and good sphericity because of the addition of the MMA and provided more adsorption sites for the Cd(Ⅱ)ions.The maximum adsorption capacity of Cd(Ⅱ)on the AAM-MSM was 39.98 mg·g^(-1).The adsorbents were superparamagnetic,and the saturation magnetization was 16.7 A·m^(2)·kg^(-1).Additionally,the adsorption isotherms and kinetics of the adsorption process were further investigated.The process of Cd(Ⅱ)ions adsorbed onto the AAM-MSM could be described more favorably by the pseudo-second-order kinetic and Langmuir isothermal adsorption models,which suggested that the chemical reaction process dominated the adsorption process for the Cd(Ⅱ)and chemisorption was the rate-controlling step during the Cd(Ⅱ)removal process.

Influence of Zr, Ce, and La on Co_3O_4 catalyst for CO_2 methanation at low temperature

The Co_3O_4 and Zr-,Ce-,and La-Co_3O_4 catalysts were prepared,characterized,and applied to produce CH_4 from CO_2 catalytic hydrogenation in low temperature as 140–220°C.The results indicated that the addition of Zr,Ce,or La to the Co_3O_4 decreased the crystallite sizes of Co and the outer-shell electron density of Co^(3+),and increased the specific surface area,which would provide more active sites for the CO_2 methanation.Especially,the addition of Zr also changed the reducing state of Co_3O_4 via an obvious change in the interaction between Co_3O_4 and ZrO_2.Furthermore,Zr doped into the Co_3O_4 increased the basic intensity of the weak and medium basic sites,as well as the amount of Lewis acid sites,and Br?nsted acid sites were also found on the Zr-Co_3O_4 surface.The introduction of Zr,Ce,or La favored the production of CH_4,and the Zr-Co_3O_4catalyst exhibited the highest CO_2 conversion(58.2%)and CH_4 selectivity(100%)at 200°C,and 0.5 MPa with a gaseous hourly space velocity of 18,000 ml·g^(-1)_(cat)·h^(-1),and the catalytic activity of CO_2methanation for the Zr-,Ce-,and La-Co_3O_4 exhibited more stable than Co_3O_4 in a 20-h reaction.

Controlled synthesis of Mn_(x)Cd_(1-x)S for enhanced visible-light driven photocatalytic hydrogen evolution

Ternary sulfide solid solutions have garnered great attention in photocatalytic water splitting due to their tunable electronic property,low cost,and sufficient light-absorption performance.Herein,a series of Mn_(x)Cd_(1-x)S samples with different Mn/Cd molar ratios were synthesized by solvothermal method and used for photocatalytic hydrogen production under visible light.The Mn_(0.2)Cd_(0.8)S and Mn_(0.4)Cd_(0.6)S are demonstrated to be the solid so-lutions,while Mn_(0.6)Cd_(0.4)S and Mn_(0.8)Cd_(0.2)S consist of Mn_(x)Cd_(1-x)S solid solution and MnS.In addition,the Mn_(0.4)Cd_(0.6)S exhibits the highest photocatalytic performance with the H_(2) production rate of 185.95μmol·h^(-1),which is 4.7 times higher than that of CdS.Without cocatalyst,the quantum efficiency of Mn_(0.4)Cd_(0.6)S reaches 2.04%at 400 nm.In addition,the Mn_(0.4)Cd_(0.6)S solid solution also shows high stability during the photocatalytic H_(2) production reaction.The effect of Mn/Cd molar ratio on the microstructure,band gap structure,and photo-catalytic hydrogen production performance of Mn_(x)Cd_(1-x)S was revealed systematically.The excellent photo-catalytic H_(2) production performance of Mn_(0.4)Cd_(0.6)S solid solution is mainly due to its enhanced reducing potential and high charge separation efficiency.

Bi-, Y-Codoped TiO2 for Carbon Dioxide Photocatalytic Reduction to Formic Acid under Visible Light Irradiation

Bi- and Y-codoped TiO2 photocatalysts were synthesized through a sol-gel method, and they were applied in the photocatalytic reduction of CO2 to formic acid under visible light irradiation. The results revealed that, after doping Bi and Y, the surface area of TiO2 was increased from 5.4 to 93.1 m2/g when the mole fractions of doping Bi and Y were 1.0% and 0.5%, respectively, and the lattice structures of the photocatalysts changed and the oxygen vacancies on the surface of the photocatalysts formed, which would act as the electron capture centers and slow down the recombination of pho- to-induced electron and hole. The photocurrent spectra also proved that the photocatalysts had better electronic transmission capacities. The HCOOH yield in CO2 photocatalytic reduction was 747.82 μmol/gcat by using 1% Bi-0.5% Y-TiO2 as a photocatalyst. The HCOOH yield was 1.17 times higher than that by using 1% Bi-TiO2, and 2.23 times higher than that by using pure TiO2. Furthermore, the 1% Bi-0.5% Y-TiO2 showed the highest apparent quantum efficiency （AQE） of 4.45%.

Preparation of InYO_3 catalyst and its application in photodegradation of molasses fermentation wastewater

An InYO 3 photocatalyst was prepared through a precipitation method and used for the degradation of molasses fermentation wastewater. The InYO 3 photocatalyst characterized by X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectroscopy, surface area and porosimetry. Energy band structures and density of states were achieved using the Cambridge Serial Total Energy package （CASTEP）. The results indicated that the photodegradation of molasses fermentation wastewater was significantly enhanced in the presence of InYO 3 when compared with PbWO 4 . The calcination temperature was found to have a significant effect on the photocatalytic activity of InYO 3 . Specifically, InYO 3 calcined at 700°C had a considerably larger surface area and lower reflectance intensity and showed higher photocatalytic activity. The mathematical simulation results indicated that InYO 3 is a direct band gap semiconductor, and its conduction band is composed of In 5p and Y 4d orbitals, whereas its valence band is composed of O 2p and In 5s orbitals.