Carbon dioxide adsorption of two-dimensional carbide MXenes

Two-dimensional carbide MXenes(Ti_3C_2T_x and V_2CT_x)were prepared by exfoliating MAX phases(Ti_3AlC_2 and V_2AlC)powders in the solution of sodium fluoride(NaF)and hydrochloric acid(HCl).The specific surface area(SSA)of as-prepared Ti_3C_2T_x was 21 m^2/g,and that of V_2CT_x was 9 m^2/g.After intercalation with dimethylsulfoxide,the SSA of Ti_3C_2T_x was increased to 66 m^2/g;that of V_2CT_x was increased to 19 m^2/g.Their adsorption properties on carbon dioxide(CO_2)were investigated under 0–4 MPa at room temperature(298 K).Intercalated Ti_3C_2T_x had the adsorption capacity of 5.79 mmol/g,which is close to the capacity of many common sorbents.The theoretical capacity of Ti_3C_2T_x with the SSA of 496 m^2/g was up to 44.2 mmol/g.Additionally,due to high pack density,MXenes had very high volume-uptake capacity.The capacity of intercalated Ti_3C_2T_(x )measured in this paper was 502 V·v^(–1).This value is already higher than volume capacity of most known sorbents.These results suggest that MXenes have some advantage features to be researched as novel CO_2 capture materials.

Graphene-like h-BN supported polyhedral NiS_(2)/NiS nanocrystals with excellent photocatalytic performance for removing rhodamine B and Cr(Ⅵ)

Human health is deteriorating due to the effluent containing heavy metal ions and organic dyes.Hence,photoreduction of Cr(Ⅵ)to Cr(Ⅲ)and degradation of rhodamine B(RhB)using a novel photocatalyst is particularly important.In this work,h-BN/NiS_(2)/NiS composites were prepared via a simple solvothermal method and a double Z-scheme heterojunction was constructed for efficiently removing RhB and Cr(Ⅵ).The 7 wt-%h-BN/NiS_(2)/NiS composites were characterized via a larger specific surface area(15.12 m^(2)·g^(−1)),stronger light absorption capacity,excellent chemical stability,and high yield of electrons and holes.The experimental result indicated that the photoreduction efficiency of the 7 wt-%h-BN/NiS_(2)/NiS photocatalyst achieved 98.5%for Cr(Ⅵ)after 120 min,which was about 3 times higher than that of NiS_(2)/NiS(34%).However,the removal rate of RhB by the 7 wt-%h-BN/NiS_(2)/NiS photocatalyst reached 80%.This is due to the double Z-scheme heterojunction formed between NiS_(2)/NiS and h-BN,which improved the charge separation efficiency and transmission efficiency.Besides,the influence of diverse photogenerated electron and hole scavengers upon the photoreduction of Cr(Ⅵ)was studied,the results indicated that graphene-like h-BN promoted transportation of photoinduced charges on the surface of the h-BN/NiS_(2)/NiS photocatalyst via the interfacial effects.

Construction of hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures for TEA detection

Construction of heterojunction has been considered as an efficient strategy to enhance the gas-sensing performances of metal oxide semiconductors.On this basis,hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures were synthesized by partial oxidation of In_(2)S_(3) precursors which were obtained via a facile hydrothermal method.Besides,gas sensors based on the acquired materials were fabricated to investigate their sensing performances toward triethylamine(TEA).The results reveal that the gas sensor based on In_(2)O_(3)/In_(2)S_(3) exhibits a high response of 37 at 300℃ toward 0.45 mg/L TEA,which is 3.7 times higher than that of bare In_(2)O_(3).Meanwhile,it also possesses fast response/recovery time(19 s/154 s),good repeatability,selectivity and long-term stability.The excellent sensing performances toward TEA are mainly attributed to the massive oxygen vacancy defects and heterojunction formed between In_(2)O_(3) and In_(2)S_(3).This work provides a facile temperature-dependent route to controllably synthesize hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures,and the In_(2)O_(3)/In_(2)S_(3) sensor shows great application prospects in TEA detection.