氧化铈空心球可控合成及其对Pt基催化剂电催化性能的影响

采用水热合成法,以碳球为模板,改变焙烧升温速率,控制影响铈物种的扩散、渗透及碳球结构的收缩率,制备了单、双壳层CeO_2空心球。通过微波辅助乙二醇还原氯铂酸法制备了Pt-CeO_2/RGO催化剂,研究了CeO_2空心球的添加对Pt基催化剂电催化性能的影响。利用X射线衍射仪(XRD)、比表面积及孔径分析仪(BET)、扫描电镜(SEM)和电子能谱(EDAX)、透射电镜(TEM)、X射线光电子能谱(XPS)对CeO_2及催化剂的微观结构进行了表征,利用电化学工作站对催化剂进行电化学性能测试。结果表明:单、双壳层CeO_2空心球的比表面积为124.44 m2/g、140.95 m2/g,孔容为0.014427 cm3/(g·nm)、0.018605 cm3/(g·nm),孔径分布在2~4 nm范围内。催化剂中的CeO_2保持原有的球状形貌,Pt纳米粒子主要分布在CeO_2附近;当RGO∶CeO_2=1∶2时,添加了双壳层CeO_2空心球的Pt-CeO_2/RGO催化剂的电催化性能最优,电化学活性表面积为94.27 m2/g,对乙醇氧化的峰电流密度值为613.54 A/g,1000 s的稳态电流密度值为135.45 A/g。

钠米钙钛矿复合氧化物的析氧电催化性质的研究

用循环伏安、线性伏安法等电化学方法研究了La0 8Sr0 2 Fe1 yAlyO3

不同活性焦载体对V_2O_5/AC催化剂脱硫活性的影响

活性焦载体的选择是制备高活性烟气脱硫催化剂的关键。以四种煤制活性焦(AC)为载体,制得了系列V2O5/AC催化剂。通过脱硫活性评价、催化氧化能力测试和孔结构分析表明,AC表面的高活性氧化位较少,担载V2O5使AC表面产生了新的高活性氧化位,其脱硫活性显著提高;V2O5在具有高比表面积和较大孔容的载体上分散性较好,能够形成较多的高活性氧化位、增强催化氧化能力。从选择V2O5/AC催化剂载体的角度考虑,载体自身的氧化性对催化剂的脱硫活性没有影响,对脱硫活性起重要作用的是载体比表面积和孔容的大小。

String and Ball-Like TiO_2/rGO Composites with High Photo-catalysis Degradation Capability for Methylene Blue

Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO_2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removalrate of 86.0% for methylene blue and its reaction rate constant(5.27 × 10^(-3) min^(-1)) was much higher than those of pure string and ball-like TiO_2(ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which~?O_2^- and~·OH were the main oxidizing groups. This work of fers new insights into a better design and preparation of novelcomposite materials for the removalof organic dyes.

Water oxidation catalytic ability of polypyridine complex containing a μ-OH, μ-O_2 dicobalt(iii) core

Two polypyridine complexes containingμ‐OH,μ‐O2dicobalt(III)cores,[(TPA)CoIII(μ‐OH)(μ‐O2)CoIII(TPA)](ClO4)3and[(BPMEN)CoIII(μ‐OH)(μ‐O2)CoIII(BPMEN)](ClO4)3(TPA=tris(2‐pyridylmethyl)amine,BPMEN=N,N′‐dimethyl‐N,N′‐bis(pyridin‐2‐ylmethyl)ethane‐1,2‐diamine),have previously been reported as inactive in the light‐driven water oxidation reaction(ACS Catal.,2016,6,5062?5068).Herein,another dicobalt(III)compound,μ‐OH,μ‐O2‐[{(enN4)2Co2}](ClO4)3(enN4=1,6‐bis(2‐pyridyl‐2,5‐diazaocta‐2,6‐diene),with a similar core structure was synthesized,characterized,and applied to the light‐driven water oxidation reaction.Collective experiments showed that the complex itself was also inactive in the light‐driven water oxidation,and that the activity observed originated from Co(II)impurities.This research establishes that complexes possessing aμ‐OH,μ‐O2dicobalt(III)core structure are not appropriate choices for true molecular catalysts ofwater oxidation.

CeO2形貌对Pt基阳极催化剂性能的影响

采用水热合成法在不同温度（300、400和500℃）下制备了比表面积分别为174.72、120.15和101.13 m2/g,孔径均在24 nm范围的帚状CeO2。通过微波辅助乙二醇还原氯铂酸法制备了CeO2修饰的石墨烯负载Pt（Pt-CeO2/C）催化剂。探究不同焙烧温度制备的CeO2对Pt-CeO2/C催化剂微观结构及电催化性能的影响。结果表明：随帚状CeO2焙烧温度的降低,催化剂的催化性能、稳定性及抗中毒能力随之增强。添加了帚状CeO2的Pt-CeO2/C催化剂的催化性能、稳定性和抗中毒能力优于传统的Pt/C。帚状CeO2焙烧温度为300℃时,Pt-CeO2/C催化剂的电催化性能最好,其电化学活性表面积为102.83 m2/g,峰电流密度为757.17 A/g,1 100 s的稳态电流密度为108.17 A/g。

Theoretical insight into methanol steam reforming on indium oxide with different coordination environments

Indium oxide(In_2O_3) has demonstrated to be an effective non-noble metal catalyst for methanol steam reforming reaction(MSR).However, the reaction mechanism of MSR and crucial structure-activity relations determining the catalytic performance of In_2O_3 are still not fully understood yet. Using density functional theory(DFT) calculation, we systematically investigate the MSR process over a high-index In_2O_3(211) and a favoured catalytic cycle of MSR is determined. The results show that In_2O_3(211) possesses excellent dehydrogenation and oxidizing ability, on which CH_3 OH can readily adsorb on the In4 c site and be easily activated by the reactive lattice oxygens, resulting in a total oxidation into CO_2 rather than CO, while the H_2 formation through surface H–H coupling limits the overall MSR activity because of the strong H adsorption on the two-coordinated lattice O(O_(2c)). Our analyses show that the relatively inert three-coordinated lattice O(O_(3c)) could play an important catalytic role. To uncover the influence of the local coordination of surface In atoms and lattice O on the catalytic activity, we evaluate the activity trend of several types of In_2O_3 surfaces including(211),(111), and(100) by examining the rate-limiting, which reveals the following activity order:(211)>(111)>(100). These findings provide an in-depth understanding on the MSR reaction mechanism over In_2O_3 catalysts and some basic structure-activity relations at the atomic scale, could facilitate the rational design of In_2O_3-based catalysts for MSR by controlling the local coordination environment of surface active sites.

Unique Cd1-xZnxS@WO3-x and Cd1-xZnxS@WO3-x/CoOx/NiOx Z-scheme photocatalysts for efficient visible-light-induced H2 evolution

Artificial Z-scheme photocatalytic systems have received considerable attention in recent years because they can achieve wide light-absorption, high charge-separation efficiency, and strong redox ability simultaneously. Nevertheless, it is still challenging to exploit low-cost and stable Zscheme photocatalysts with highly-efficient H2 evolution from solar water-splitting so far. Herein, we report a novel all-solidstate Z-scheme photocatalyst Cd1-xZnxS@WO3-x consisting of Cd1-xZnxS nanorods coated with oxygen-deficient WO3-x amorphous layers. The Cd1-xZnxS@WO3-x exhibits an outstanding H2 evolution reaction(HER) activity as compared with Pt-loaded Cd1-xZnxS and most WO3- and Cd S-based photocatalysts, due to the generation of stronger reducing electrons through the appropriate Zn-doping in Cd1-xZnxS and the enhanced charge transfer by introducing oxygen vacancies(W^5+/OVs) into the ultrathin WO3-x amorphous coatings. The optimal HER rate of Cd1-xZnxS@WO3- xis determined to be 21.68 mmol h^-1 g^-1, which is further raised up to 28.25 mmol h^-1 g^-1(about 12 times more than that of Pt/Cd1-xZnxS) when Cd1-xZnxS@WO3-x is hybridized by Co Ox and Ni Oxdual cocatalysts(Cd1-xZnxS@WO3-x/CoOx/NiOx)through in-situ photo-deposition. Moreover, the corresponding apparent quantum yield(AQY) at 420 nm is significantly increased from 34.6% for Cd1-xZnxS@WO3-x to 60.8% for Cd1-xZnxS@WO3-x/CoOx/NiOx. In addition, both Cd1-xZnxS@WO3-x and Cd1-xZnxS@WO3-x/CoOx/NiOx demonstrate good stability towards HER. The results displayed in this work will inspire the rational design and synthesis of high-performance nanostructures for photocatalytic applications.