CO_(2) capture and conversion to value-added products promoted by MXene-based materials

Carbon dioxide(CO_(2) ) capture and conversion is the key route for the mitigation of the greenhouse effect and utilization of carbon sources to obtain value-added products or fuels.Much attention is paid to the development of novel materials with high CO_(2) adsorption capacity and conversion rate.MXene is the graphene-like two-dimensional metal carbide/nitride/carbonitride owning favorable structure,morphology,high surface-bulk ratio,and physicochemical properties.Here,we review the CO_(2) capture,sensing,and conversion by MXene and MXene-based materials.Furthermore,the underlying mechanism involved the capture,sensing,and conversion of CO_(2) is summarized.This review would open a new horizon for CO_(2) valorization with high efficiency and promising widespread applications.

Engineering of SnO_(2)/TiO_(2) heterojunction compact interface with efficient charge transfer pathway for photocatalytic hydrogen evolution

Fabricating an efficient charge transfer pathway at the compact interface between two kinds of semiconductors is an important strategy for designing hydrogen production heterojunction photocatalysts.In this work,we prepared a compact,stable and oxygen vacancy-rich photocatalyst(SnO_(2)/TiO_(2) heterostructure)via a simple and reasonable in-situ synthesis method.Briefly,SnCl_(2)–2H_(2)O is hydrolyzed on the TiO_(2) precursor.After the pyrolysis process,SnO_(2) nanoparticles(5 nm)were dispersed on the surface of ultrathin TiO_(2) nanosheets uniformly.Herein,the heterojunction system can offer abundant oxygen vacancies,which can act as active sites for catalytic reactions.Meanwhile,the interfacial contact of SnO_(2)/TiO_(2) grading semiconductor oxide is uniform and tight,which can promote the separation and migration of photogenerated carriers.As shown in the experimental results,the hydrogen production rate of SnO_(2)/TiO_(2) is 16.7 mmol h^(-1)g^(-1)(4.4 times higher than that of TiO_(2)),which is owing to its good dynamical properties.This work demonstrates an efficient strategy of tight combining SnO_(2)/TiO_(2) with abundant oxygen vacancies to improve catalytic efficiency.

N-doped carbon supported Pd catalysts for N-formylation of amines with CO2/H2

Using mesoporous N-doped carbons(NCs)derived from glucose and melamine as the supports,a series of Pd/NC catalysts were prepared,in which Pd nanoparticles with average size<2.0 nm were uniformly distributed on the supports.It was indicated that the resultant Pd/NC catalysts were effective for N-formylation of amines with CO_2and H_2in ethanol without any additives.Especially,the catalyst Pd/NC-800-6.9%containing quaternary N showed the best performance,affording a series of formylamides in good or even excellent yields.Further investigation reveals that the interaction between the Pd nanoparticles and quaternary nitrogen in the NC support was responsible for the good performance of the catalyst.

Synergetic enhancement of surface reactions and charge separation over holey C_(3)N_(4)/TiO_(2)2D heterojunctions

Efficient charge separation and rapid interfacial reaction kinetics are crucial factors that determine the efficiency of photocatalytic hydrogen evolution.Herein,a fascinating 2D heterojunction photocatalyst with superior photocatalytic hydrogen evolution performance–holey C_(3)N_(4)nanosheets nested with TiO_(2)nanocrystals(denoted as HCN/TiO_(2))–is designed and fabricated via an in situ exfoliation and conversion strategy.The HCN/TiO_(2)is found to exhibit an ultrathin 2D heteroarchitecture with intimate interfacial contact,highly porous structures and ultrasmall TiO_(2)nanocrystals,leading to drastically improved charge carrier separation,maximized active sites and the promotion of mass transport for photocatalysis.Consequently,the HCN/TiO_(2)delivers an impressive hydrogen production rate of 282.3 lmol h^(-1)per10 mg under AM 1.5 illumination and an apparent quantum efficiency of 13.4%at a wavelength of 420 nm due to the synergetic enhancement of surface reactions and charge separation.The present work provides a promising strategy for developing high-performance 2D heterojunctions for clean energy applications.

A Novel Route to Synthesize N,N-Dimethyl Arylmethylamines from Aryl Aldehydes, Hexamethylenetetramine and Hydrogen

Developing simple and green routes to access valuable chemicals is of significance.Herein,we present a green and novel route to synthesize N,N-dimethyl arylmethylamines(DAMAs)from hexamethylenetetramine(HMTA)and aryl aldehydes in the presence of hydrogen,and a series of DAMAs can be obtained in good yields.This approach opens the precedent for HMTA as N,N-dimethylamine source to synthesize chemicals with N,N-dimethylamine group,which has promising applications for N-containing chemicals synthesis.

Supramolecular precursor derived loofah sponge-like Fe_(2)O_(x)/C for effective synergistic reaction of Fenton and photocatalysis

Fenton or photocatalytic degradations of organic contaminants are recognized as promising approaches to address the increasing environmental pollution issues.Herein,we develop the effective synergistic catalysis reaction of Fenton and photocatalysis based on a loofah sponge-like Fe_(2)O_(x)/C nanocomposite,which exhibits excellent nitrobenzene photocatalytic degradation property.It is noted that Fe2O3 nanoparticles with surface Fe^(2+) species were encapsulated with an ultrathin carbon layer(denoted as Fe_(2)O_(x)/C)via a supramolecular self-sacrificing template and following thermal treatment process.The experimental results indicated that the thin layer carbon coating not only inhibited the Fe iron leaching from the Fe_(2)O_(x)but also prompted the separation and transferring of electrons–hole pairs.The introduction of Fe_(2)O_(x)/C enables the Fenton reaction to induce a rapid Fe^(2+)/Fe^(3+)cycle,and meanwhile,together with the photocatalytic reaction to produce continuous active substances for the subsequent degradation catalytic reaction without successive H2O2,resulting in the inexpensive and the effective photocatalytic procedure.As a result,100%nitrobenzene(100 mg/L)was degraded and 97%of the organic carbon was mineralized in 90 min using the Fe_(2)O_(x)/C(0.1 g/L)at a low H_(2)O_(2) dosage(0.50 mM),under air mass(AM)1.5 irradiation.Theoretical calculations confirmed that the Fe_(2)O_(x)/C-600 with thin carbon layer promoted the dissociation of H2O2 and the·OH desorption.The synergistic catalysis of this work may provide new ideas for low-cost and more efficient treatment of pollutants.