Triple the steady-state reaction rate by decorating the In_(2)O_(3)surface with SiO_(x)for CO_(2)hydrogenation

Indium oxide(In_(2)O_(3)),as a promising candidate for CO_(2)hydrogenation to C_(1) products,often suffers from sintering and activity decline,closely related to the undesirable structural evolution under reaction conditions.Based on the comprehension of the dynamic evolution,this study presents an efficient strategy to alleviate the agglomeration of In_(2)O_(3)nanoparticles by the surface decoration with highly dispersed silica species(SiO_(x)).Various structural characterizations combined with density functional theory calculations demonstrated that the sintering resulted from the over-reduction,while the enhanced stability originated from the anchoring effect of highly stable In-OSi bonds,which hinders the substantial formation of metallic In(In^(0))and the subsequent agglomeration.0.6Si/In_(2)O_(3)exhibited CO_(2)conversion rate of10.0 mmol g^(-1)h^(-1)at steady state vs.3.5 mmol g^(-1)h^(-1)on In_(2)O_(3)in CO_(2)hydrogenation.Enhanced steady-state activity was also achieved on Pd-modified catalysts.Compared to the traditional Pd/In_(2)O_(3)catalyst,the methanol production rate of Pd catalyst supported on 0.6Si/In_(2)O_(3)was enhanced by 23%,showing the potential of In_(2)O_(3)modified by SiO_(x)in serving as a platform material.This work provides a promising method to design new In_(2)O_(3)-based catalysts with improved activity and stability in CO_(2)hydrogenation.

Photocatalysts for degradation of dyes in industrial effluents:Opportunities and challenges

Discharging dye contaminants into water is a major concern around the world.Among a variety of methods to treat dye-contaminated water,photocatalytic degradation has gained attention as a tool for treating the colored water.Herein,we review the recent advancements in photocatalysis for dye degradation in industrial effluents by categorizing photocatalyst materials into three generations.First generation photocatalysts are composed of single-component materials (e.g.,TiO2,ZnO,and CdS),while second generation photocatalysts are composed of multiple components in a suspension (e.g.,WO3/NiWO4,BiOl/ZnTiOa,and C3N4/Ag3VO4).Photocatalysts immobilized on solid substrates are regarded as third generation materials (e.g.,FTO/WO3-ZnO,Steel/TiO2-WO3,and Glass/P-TiO2).Photocatalytic degradation mechanisms,factors affecting the dye degradation,and the lesser-debated uncertainties related to the photocatalysis are also discussed to offer better insights into environmental applications.Furthermore,quantum yields of different photocatalysts are calculated,and a performance evaluation method is proposed to compare photocatalyst systems for dye degradation.Finally,we discuss the present limitations of photocatalytic dye degradation for field applications and the future of the technology.

Catalytically active interfaces in titania nanorod-supported copper catalysts for CO oxidation

One-dimensional titanium dioxide nanorod(TNR)-supported Cu catalysts(2.5 wt.%-12.5 wt.%)were synthesized using deposition-precipitation.X-ray photoelectron spectroscopy,temperature programmed reduction and CO chemisorption measurements showed that Cu doping over TNR offered metal-support interactions and interfacial active sites that had a profound impact on the catalytic performance.The role of the Cu-TNR interface was investigated by comparing the catalytic activity of Cu-TNR catalysts with that of pure CuO nanoparticles in CO oxidation.The presence of highly dispersed copper species,a high number of interfacial active sites,CO adsorption capacity and surface/lattice oxygen were found to be responsible for the excellent activity of 7.5CU-TNR(ie,Cu loading of 7.5 wt.%on TNR).Moreover,the Cu-TNR catalysts followed the Langmuir-Hinshelwood reaction mechanism with 7.5CU-TNR,exhibiting an apparent activation energy of 44.7 kJ/mol.The TNR-supported Cu catalyst gave the highest interfacial catalytic activity in medium-temperature CO oxidation(120-240℃)compared to other commonly used supports,including titanium dioxide nanoparticles(TiO2-P25),silica(SiO2)and alumina(Al20g)in which copper species were nonhomogeneously dispersed.This study confirms that medium-temperature CO oxidation is highly sensitive to the morphology and structure of the supporting material.