A simple ultrasono-synthetic route of PbSe-graphene-TiO2 ternary composites to improve the photocatalytic reduction of CO2

The present work investigates the photocatalytic reduction of CO₂ to CH₃OH with a PbSe-G-TiO₂ photocatalyst. A heterogeneous PbSe-G-TiO₂ nanocomposite was prepared via ultra-sonication and was characterized via XRD, SEM, HRTEM, Raman, XPS, and DRS measurements. The photocatalytic efficiencies of the prepared sample were further characterized by GC for the photoreduction of CO₂ to CH₃OH under UV and visible light. The prepared PbSe-G-TiO₂ ternary nanocomposites with an optimum GO loading of 6% exhibited outstanding photocatalytic activity (4.35 µmol g^?1 h^?1) after 48 hours of reaction. This indicated that the photocatalytic efficiency was mostly dependent on the weight ratio of graphene, sacrificial material Na₂SO₃/Na₂S, and the type of reactant. This work provides an accessible way to improve the response of a graphene-based TiO₂ photocatalyst to UV/visible light and to facilitate its application in environmental remediation.     

A hierarchical heterostructure of CdS QDs confined on 3D ZnIn2S4 with boosted charge transfer for photocatalytic CO2 reduction

Metal sulfide based materials as photocatalysts for energy conversion are essential to produce value-added chemical fuels,but their intrinsically slow carrier dynamics and low activity are yet to be resolved.Herein,we developed a unique heterogeneously nanostructured ZnIn₂S₄-CdS heterostructure that involves zero-dimensional(0D)CdS quantum dots uniformly confined on three-dimensional(3D)ZnIn₂S₄nanoflowers,which achieves an excellent catalytic performance of CO₂ photoconversion under visible-light irradiation.The obtained hierarchical heterostructure can significantly enhance the light harvesting,shorten the migration distance of carriers,and obviously accelerate the transport of electrons.As evidenced by the ultrafast transient absorption spectroscopy,the formed interface can effectively facilitate charge separation and transport.This work opens up a new avenue to carefully design the elaborate heterostructures for achieving optimal charge separation efficiency by lowering interfacial kinetic barriers and energy losses at the interface.     

具有近红外吸收的二维/三维ZnIn2S4/氮掺杂石墨烯光催化剂的制备及其高效CO2捕获和光催化还原性能（英文）

具有宽光谱太阳能利用的分等级异质结光催化剂,正成为一种新兴的先进光催化材料,被应用于太阳能驱动二氧化碳转化为高附加值的化学原料.本工作通过水热法使二维硫化铟锌纳米墙垂直生长于三维氮掺杂石墨烯泡沫上,形成分等级异质结光催化剂.该催化剂展现出优异的光热转换效率、选择性捕获CO2和光催化还原CO2的能力.在273 K和1个大气压条件下,负载1 wt%氮掺杂石墨烯泡沫的复合催化剂表现出最优异的性能,其中对CO2和N2的吸附选择性为30.1,并且对CO2的等量吸附热为48.2 kJ mol^-1.在无助催化剂和牺牲剂的条件下,负载1 wt%氮掺杂石墨烯泡沫的复合催化剂,其光催化转化CO2为CH4、CO和CH3OH的效率分别是纯的硫化铟锌的9.1、3.5和5.9倍.该增强效应得益于三维石墨烯泡沫高度开放的网状结构,良好的CO2吸附能力和两种组份之间的强相互作用.此外,利用原位照射X射线光电子能谱仪和开尔文探针技术分析了电荷转移的方向,本工作为设计高效太阳能转化分等级异质结光催化剂开辟了新的思路.     

Metal-organic frameworks based materials for photocatalytic CO2 reduction

Photocatalytic conversion of CO₂ to valuable chemicals by solar irradiation is a hugely attractive process due to its potential to offset both the energy and economic penalties of CO₂ capture and sequestration. Metal-organic frameworks (MOFs) have recently been explored as photocatalysts for this processing owing to their promising photochemical and textural properties. Papers to date are collated and reviewed to highlight advances made in MOF photocatalysts through novel synthesis and analytical methods. These are compared with key metrics highlighting the range of materials and methods used to show the diversity and novelty of this emerging field. Knowledge gaps were noted in order to propose potential routes for further improvements in catalyst and reactor design.

This review was chosen as a runner up of the 2017 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining, run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged     

Cd掺杂ZnIn2S4的制备及光催化降解偶氮胭脂红B的性能研究

采用水热法制备了Cd掺杂ZnIn₂S₄光催化剂。利用X射线粉末衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM-EDS）、X射线光电子能谱（XPS）、紫外-可见吸收光谱（UV-Vis）及光致发光光谱（PL）等手段对光催化剂进行了表征。结果表明,Cd掺杂虽没有改变ZnIn₂S₄的晶型,但使禁带宽度变窄,吸收边红移,表面缺陷和氧空位增加,有利于光生载流子的有效分离;而且镉掺杂后催化剂的电化学阻抗减小,有利于光生载流子的快速传输,因此微量Cd掺杂后ZnIn₂S₄催化降解偶氮胭脂红B的光催化性能明显提高,105 min内降解率可达93%,且循环稳定性好。     

Excellent visible light photocatalytic properties of novel graphene based CdLa2S4/TiO2 heterojunction nanocomposite

This paper introduced one pot method for the synthesis of hybrid CdLa₂S₄-graphene/TiO₂ nanocomposite. The surface properties seen by SEM present a characterization of the texture on CdLa₂S₄-graphene/TiO₂ composites and showed a homogenous composition in the particles. The EDX spectra for the elemental identification showed the presence of C, O and Ti with strong Cd, La and S peaks for the CdLa₂S₄-graphene/TiO₂ nanocomposite. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the photocatalytic effect increase in the case with the modified CdLa₂S₄.From the photocatalytic results, the excellent activity of CdLa₂S₄-graphene/TiO₂ nanocompositefor degradation of methylene blue (MB) and Texbrite BA-L (TBA) undervisible irradiation could be attributed to both the effects between photocatalysis of the supported TiO₂ and charge transfer of the grapheme nanosheet, and the introduction of CdLa₂S₄ to enhance the photogenerated electrons.     

Enhanced CH4 selectivity in CO2 photocatalytic reduction over carbon quantum dots decorated and oxygen doping g-C3N4

Nano Research - Graphitic carbon nitride (g-C3N4, CN) exhibits inefficient charge separation, deficient CO2 adsorption and activation sites, and sluggish surface reaction kinetics, which have been...     

Synthesis of Ag@TiO2/NiFe2O4 ternary nanostructures and evaluation of their photocatalytic activities

Journal of Materials Science: Materials in Electronics - Synthesis and characterization of novel and ternary photocatalysts Ag@TiO2/NiFe2O4 for the three potential applications, such as...     

CO2 reduction to CH4 with H2 on photoirradiated TS-1

CO₂ reduction on reduced titanium silicalite (TS-1) with photoirradiation in the presence of H₂ was investigated in a closed circulation system. CO₂ was reduced to give CH₄ under u.v. irradiation, which TS-1 absorbs. The amount of the carbon species on TS-1 after photoirradiation indicated that all Ti atoms in the framework may act as a photocatalytic site. Infrared spectrum of TS-1 after the reaction showed that CH₂ and CH₃ were left on TS-1.     

New ternary anti-Th3P4-type europium compounds

Nonmetallic chalcopnictides of composition Eu₄Y₂X (Y = pnigogen, X = chalcogen) have been found to crystallize in the anti-Th₃P₄ type of structure. Anion ordering or a tetragonal distortion of the cubic cell could not be detected. Magnetic ordering at low temperatures is ferromagnetic in the lighter and antiferromagnetic in the heavier compounds. Isostructural chalcopnictides are expected to exist with Ca, Sr, Ba and (with the heavier anions) with Sm and Yb, as was confirmed in the case of Ca₄Bi₂Te, Sm₄Bi₂Te and Yb₄Bi₂Te.     

Preparation of Z-scheme Au-Ag2S/Bi2O3 composite by selective deposition method and its improved photocatalytic degradation and reduction activity

In this work, Z-scheme Ag₂S/Bi₂O₃ composites were fabricated through the precipitation of Ag₂S nanoplates on the surface of Bi₂O₃ microrods. Consequently, Au nanoparticles were selectively deposited on the Ag₂S nanoplates surface to obtain.Au-Ag₂S/Bi₂O₃ composites using near-infrared light photodeposition method. The characterization results indicate that the Ag₂S nanoplates were uniformly anchored on Bi₂O₃ surface, and Au nanoparticles were highly dispersed on the surface of Ag₂S nanoplate instead of Bi₂O₃. Acid orange 7 (AO7), Rhodamine B (RhB) and Cr(VI) were chosen as model reactant for the evaluation of photocatalytic degradation and reduction activity of the products under simulated sunlight irradiation. After the decoration of Ag₂S nanoplates, the photocatalytic activity of Ag₂S/Bi₂O₃ is much higher than that of bare Bi₂O₃, and the optimal catalytic efficiency is achieved by 12 %Ag₂S/Bi₂O₃ sample. More importantly, the photocatalytic activity of 12 %Ag₂S/Bi₂O₃ sample can be further enhanced by the selective decoration Au nanoparticles on the Ag₂S nanoplates. Among the ternary composites, 2Au-12 %Ag₂S/Bi₂O₃ sample with the Au content of 2% exhibits highest catalytic efficiency for 60 min (AO7: 96%; RhB: 56%; Cr(VI): 65%). The possible mechanism for the improvement of the photocatalytic activity of Bi₂O₃ by Ag₂S and Au decoration was proposed.     

燃烧法合成CuAl2O4及其光催化性能的研究

讨论了不同的合成方法、点火温度、燃料的量、络合剂的量对燃烧法合成CuAl2O4的影响。在燃烧法中加入络合剂柠檬酸合成前驱物，可以成功地合成出粒径较均一且晶相纯度较高的纳米CuAl2O4。光催化降解甲基橙的实验表明，当pH值为7时的光催化效果较好，表观反应速率为0．003。     

CO2 reduction using hydrothermal method for the selective formation of organic compounds

The reduction of CO₂ under hydrothermal conditions has been investigated. In typical experiment, Fe-powder, Ni-powder, solvent, and CO₂ have been reacted in a batch-type micro autoclave under hydrothermal conditions for several hours. Methane, formic acid, and hydrogen were generated after treatment in water. With the rise of Ni amount, the methane yield increased while hydrogen and formic acid decreased. It is supposed that Ni has acted as a hydrogenation catalyst. In basic solution, CO₂ was converted to formic acid selectively at 300°C involved with trace of methane. Considering the reduction characteristics of formic acid, the reaction pathway has been discussed. In experiments with the mixture of Fe and Fe₃O₄, trace of methanol was detected at the experiments with less amount of metallic Fe. It is inferred that the control on the effect of reductant is indispensable for oxygenated organic compound formation. Experiment on the effect of water has been conducted using hydrogen. Ethane yield increased with the amount of water, while there was no drastic change in the yield of methane. From these results, it is supposed that the steam reforming reaction of methane was involved in the reduction of CO₂, and effected on the C–C bond formation.     

Hydrothermal synthesis of SnO2/SnS2 nanocomposite with high visible light-driven photocatalytic activity

SnO₂/SnS₂ nanocomposite with a heterojunction structure (that is, SnO₂ nanoparticles-decorated SnS₂ nanoplates) was synthesized via the hydrothermal reaction between SnO₂ nanoparticles and thioacetamide in 5 vol.% acetic acid aqueous solution at 150 °C for 3 h, and characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the hydrothermally synthesized SnO₂/SnS₂ nanocomposite was tested by degrading methyl orange in distilled water under visible light (λ > 420 nm) irradiation. It was found that the hydrothermally synthesized SnO₂/SnS₂ nanocomposite exhibited superior photocatalytic activity to SnO₂ nanoparticles, SnS₂ nanoplates and physically mixed SnO₂/SnS₂ nanocomposite. The heterojunction structure of the hydrothermally synthesized SnO₂/SnS₂ nanocomposite, which can facilitate interfacial electron transfer and reduce the self-agglomeration of two components, was considered to play an important role in achieving its higher photocatalytic activity.     

Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production

With its unique electronic and optical properties, graphene is proposed to functionalize and tailor titania photocatalysts for improved reactivity. The two major solution-based pathways for producing graphene, oxidation-reduction and solvent exfoliation, result in nanoplatelets with different defect densities. Herein, we show that nanocomposites based on the less defective solvent-exfoliated graphene exhibit a significantly larger enhancement in CO(2) photoreduction, especially under visible light. This counterintuitive result is attributed to their superior electrical mobility, which facilitates the diffusion of photoexcited electrons to reactive sites.