TiO_(2) nanofiber-supported copper nanoparticle catalysts for highly efficient methane conversion to C1 oxygenates under mild conditions

The selective oxidation of methane under mild conditions remains the“Holy Grail of Catalysis”.The key to activating methane and inhibiting over-oxidation of target oxygenates lies in designing active centers.Copper nanoparticles were loaded onto TiO_(2) nanofibers using the photo-deposition method.The resulting catalysts were found to effectively convert methane into C1 oxygenated products under mild conditions.Compared with previously reported catalysts,it delivers a superior performance of up to 2510.7 mmol·g_(Cu)^(-1)·h^(-1) productivity with a selectivity of around 100%at 80℃for 5 min.Microstructure characterizations and density functional theory(DFT)calculations indicate that TiO_(2) in the mixed phase of anatase and rutile significantly increases the Cu^(+)/CuO ratio of the supported Cu species,and this ratio is linearly related to the formation rate of oxygen-containing species.The CuI site promotes the generation of active O species from H_(2)O_(2) dissociation on Cu_(2)O(111).These active O species reduce the energy barrier for breaking the C-H bond of CH_(4),thus boosting the catalytic activity.The methane conversion mechanism was proposed as a methyl radical pathway to form CH_(3)OH and CH_(3)OOH,and then the generated CH_(3)OH is further oxidized to HOCH_(2)OOH.

Electrochemical water oxidation by photo-deposited cobalt-based catalyst on a nano-structured TiO_(2) electrode

A cobalt-based catalyst was directly photo-deposited on the surface of a widely used n-type nano-structured semiconductor(TiO_(2)).Different thicknesses of the TiO 2 films as well as different time of photo-deposition of the Co-based catalyst on TiO_(2) films have been optimized.It was found that the electrode with 3 layers of TiO_(2) film(in 8 m thickness) and 1 hour photo-deposition of the cobalt-based catalyst by light irradiation from a 500 W Xenon lamp gave the highest current density(~5 mA/cm^(2)).Using this cobalt-modified TiO_(2) film as a working electrode in an electrochemical device,highly efficient water oxidation has been demonstrated in a pH 7.0 aqueous solution with low overpotential.

FeOOH photo-deposited perylene linear polymer with accelerated charge separation for photocatalytic overall water splitting

It is a challenge to develop single polymer-based photocatalyst for overall water splitting without adding sacrificial agents due to the insufficient driving force for charge separation and the lack of active sites of organic polymer.Metal oxyhyroxides are widely acted as co-catalyst for photoelectrocatalysis oxygen evolution reaction.Here,we firstly report the peryleno[1,12-bcd]thiophene sulfone-based linear co-polymer PS-5 for photocatalytic overall water splitting by photo-depositing simple and low-cost cocatalyst FeOOH under the visible-light illumination.The density functional theory(DFT)calculations and experimental results indicated clearly that the oxygen vacancies-richβ-FeOOH can effectively promote the separation of photo-generated excitons and provide active sites for photocatalytic oxygen evolution reaction.As a result,the average H_(2)and O_(2)production rates of optimized PS-5/β-FeOOH-0.2M reach at~170 and~76.6μmol h^(-1)g^(-1),respectively,with a stoichiometric ratio at about 2:1.This work provides a simple and low-cost method for the preparation of overall water splitting system based on polymer photocatalyst.

Highly efficient charge transfer in Cd S-covalent organic framework nanocomposites for stable photocatalytic hydrogen evolution under visible light

A facile and effective impregnation combined with photo-deposition approach was adopted to deposit cadmium sulfide(CdS)nanoparticles on CTF-1,a covalent triazine-based frameworks(CTFs).In this system,CTF-1 not only acted as supporter but also served as photocatalyst and electron donor.The performance of the obtained CdS deposited CTF-1(CdS-CTF-1)nanocomposite was evaluated by H2 evolution reaction under visible light irradiation.As a result,CdS-CTF-1 exhibited high H2 production from water,far surpassing the Cd S/CTF-1 nanocomposite,in which Cd S was deposited via solvothermal method.The high activity of CdS-CTF-1 was attributed to the confined Cd S nanoparticles with small size,leading to expose more active sites.In addition,time-resolved spectroscopy indicated that the superior performance of Cd S-CTF-1 also can be ascribed to the fast electron transfer rate and injection efficiency(KET=0.18×10^9 s^-1,ηinj=39.38%)between Cd S and CTF-1 layers,which are 3.83 times faster and 4.84 times higher than that of Cd S/CTF-1 nanocomposite.This work represents the first example on using covalent organic frameworks(COFs)as a support and electron-donor for fabricating novel Cd S-COF nanocomposite system and its potential application in solar energy transformations.