The insufficient performance of Pt and Pd benchmark catalysts remains a significant obstacle to the practical application of direct liquid fuel cells.In this study,we report a synthesis of amorphous PdSe/crystalline P...The insufficient performance of Pt and Pd benchmark catalysts remains a significant obstacle to the practical application of direct liquid fuel cells.In this study,we report a synthesis of amorphous PdSe/crystalline Pt nanoparticles(AC-PdPtSe NPs)by chemical leaching of PdPtSe NPs.AC-PdPtSe NPs display significantly enhanced activity and stability for the electrooxidation of ethylene glycol and glycerol,far surpassing that of amorphous-dominant PdPtSe NPs,commercial Pd/C,and Pt/C catalysts.Notably,the integration of crystalline and amorphous domains leverages the advantages of high electrical conductivity and a wealth of active sites,which can substantially accelerate reaction kinetics.Furthermore,detailed investigations reveal that the boundary between the Pt crystalline and PdSe amorphous phases induces a 3%surface tensile strain.The formation of amorphous-crystalline heterointerfaces optimizes the d-band states,thereby strengthening the adsorption and activation of ethylene glycol and glycerol.This study highlights the advance in phase engineering toward the development of highly active noble-metal nanostructures.展开更多
MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,f...MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,fast degradation caused by the attack of dissolved oxygen and water molecules is the main obstacle to the application of MXenes.It has come to light that the degradation preferentially takes place at defective sites and edges where defects enrich.To tackle this problem and increase the stability,herein,using Ti_(3)C_(2)T_(x)MXene as a model material,we report a simple yet efficient strategy for long term storage of MXene suspension by introducing glycerol,a typical polyhydric alcohol.The effectiveness of the strategy is evidenced by structural compositional and morphological investigations.Glycerol protects the defective sites of MXene flakes through restricting water and/or oxygen molecules from reactive sites.This is supported by ab initio molecular dynamics simulations that form hydrogen bonds between MXene and glycerol molecules just over defective sites.Following this mechanism,other polyhydric alcohols,such as ethylene glycol and propylene glycol,are also effective in stabilizing Ti_(3)C_(2)T_(x)MXene suspension.The strategy based on polyhydric alcohols has the potential to be extended to other MXenes,solving the most urgent challenge in the field of MXene engineering.展开更多
Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Lique...Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Liquefied products(LBPP) could be used as raw materials for polyurethane by reacting with 4, 4'-diphenylmethane diisocyanate(4, 4'-MDI) and PEG400 to synthesize liquefied product-based polyurethane(LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4'-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength(4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52274304,52073199).
文摘The insufficient performance of Pt and Pd benchmark catalysts remains a significant obstacle to the practical application of direct liquid fuel cells.In this study,we report a synthesis of amorphous PdSe/crystalline Pt nanoparticles(AC-PdPtSe NPs)by chemical leaching of PdPtSe NPs.AC-PdPtSe NPs display significantly enhanced activity and stability for the electrooxidation of ethylene glycol and glycerol,far surpassing that of amorphous-dominant PdPtSe NPs,commercial Pd/C,and Pt/C catalysts.Notably,the integration of crystalline and amorphous domains leverages the advantages of high electrical conductivity and a wealth of active sites,which can substantially accelerate reaction kinetics.Furthermore,detailed investigations reveal that the boundary between the Pt crystalline and PdSe amorphous phases induces a 3%surface tensile strain.The formation of amorphous-crystalline heterointerfaces optimizes the d-band states,thereby strengthening the adsorption and activation of ethylene glycol and glycerol.This study highlights the advance in phase engineering toward the development of highly active noble-metal nanostructures.
文摘MXenes have promises in myriad applications by virtue of two-dimensional nature and adjustable functional groups.To achieve the applications,MXenes are always first prepared in the form of aqueous suspension.However,fast degradation caused by the attack of dissolved oxygen and water molecules is the main obstacle to the application of MXenes.It has come to light that the degradation preferentially takes place at defective sites and edges where defects enrich.To tackle this problem and increase the stability,herein,using Ti_(3)C_(2)T_(x)MXene as a model material,we report a simple yet efficient strategy for long term storage of MXene suspension by introducing glycerol,a typical polyhydric alcohol.The effectiveness of the strategy is evidenced by structural compositional and morphological investigations.Glycerol protects the defective sites of MXene flakes through restricting water and/or oxygen molecules from reactive sites.This is supported by ab initio molecular dynamics simulations that form hydrogen bonds between MXene and glycerol molecules just over defective sites.Following this mechanism,other polyhydric alcohols,such as ethylene glycol and propylene glycol,are also effective in stabilizing Ti_(3)C_(2)T_(x)MXene suspension.The strategy based on polyhydric alcohols has the potential to be extended to other MXenes,solving the most urgent challenge in the field of MXene engineering.
基金Funded by the National Science Foundation of China(No.51263006)the Ministry of Education Ph D Advisor Class Special Fund(No.20134601110004)+2 种基金the Hainan Province of Key Projects(ZDXM20130086)the Hainan Province International Science and Technology Cooperation Specific(No.KJHZ2014-02)the Hainan Province Natural Science Foundation(No.314074)
文摘Banana pseudo-stem was liquefied in the mixture of polyhydric alcohols of polyethylene glycol(PEG400) and glycerol. Hydroxyl value of liquefied products ranged from 294.8 to 370.2 mg KOH/g and M_n was about 430. Liquefied products(LBPP) could be used as raw materials for polyurethane by reacting with 4, 4'-diphenylmethane diisocyanate(4, 4'-MDI) and PEG400 to synthesize liquefied product-based polyurethane(LBPP-PU) adhesive. To analyze in depth the creation of urethane linkage among LBPP, PEG400 and 4, 4'-MDI, factors which had effects on the residue content were all investigated. They were characterized by FT-IR and TG. The shear strength of LBPP-PU adhesive was improved when decreasing the percentage of the substitution of PEG400 by LBPP. The adhesive strength was obtained from T-peel of aspen/polyurethane adhesive joints, and the maximum lap shear strength(4.40 MPa) was obtained when 16.70% of LBPP was added to the LBPP & PEG400 system.
