Based on density functional theory calculations,the full hydrolysis of per NH3BH3 molecule to produce three hydrogen molecules on single Pt atoms supported on oxidized graphene(Pt1/Gr-O)is investigated.It is suggested...Based on density functional theory calculations,the full hydrolysis of per NH3BH3 molecule to produce three hydrogen molecules on single Pt atoms supported on oxidized graphene(Pt1/Gr-O)is investigated.It is suggested that the first hydrogen molecule is produced by the combination of two hydrogen atoms from two successive B-H bonds breaking.Then one H2O molecule attacks the left*BHNH3 group(*represents adsorbed state)to form*BH(H2O)NH3 and the elongated O-H bond is easily broken to produce*BH(OH)NH3.The second H2O molecule attacks*BH(OH)NH3 to form*BH(OH)(H2O)NH3 and the breaking of O-H bond pointing to the plane of Pt1/Gr-O results in the desorption of BH(OH)2NH3.The second hydrogen molecule is produced from two hydrogen atoms coming from two H2O molecules and Pt1/Gr-O is recovered after the releasing of hydrogen molecule.The third hydrogen molecule is generated by the further hydrolysis of BH(OH)2NH3 in water solution.The rate-limiting step of the whole process is the combination of one H2O molecule and*BHNH3 with an energy barrier of 16.1 kcal/mol.Thus,Pt1/Gr-O is suggested to be a promising catalyst for hydrolysis of NH3BH3 at room temperature.展开更多
The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen producti...The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.展开更多
The hypoxic nature of solid tumors has severely negative effects on oxygen-based photodynamic therapy.In this study,we used porous Pt nanoparticles as a catalase(CAT)nanozyme,the second near-infrared(NIR-Ⅱ)region pho...The hypoxic nature of solid tumors has severely negative effects on oxygen-based photodynamic therapy.In this study,we used porous Pt nanoparticles as a catalase(CAT)nanozyme,the second near-infrared(NIR-Ⅱ)region photothermal transition agents(PTAs),and carriers of photosensitizer chlorin e6(Ce6)to synthesize a composite nanosystem Pt-Ce6.In this system,Pt-Ce6 can continuously and stably decompose H2O2 into oxygen,thereby alleviating tumor hypoxia and improving the effect of photodynamic therapy(PDT).With 650 nm illumination,the reactive oxygen species(ROS)produced by Ce6 will decrease the mitochondrial membrane potential(MMP,ΔΨm)to release cytochrome c(Cyt-c)from the mitochondria into the cytoplasm,eventually leading to mitochondrial-mediated cellular apoptosis during the PDT process.In addition,Pt-Ce6 has good photothermal stability and high photothermal conversion efficiency(52.62%)in the NIR-II region.In U14 tumor-bearing mice,Pt-Ce6 completely suppressed tumor growth and recurrence under laser irradiation.Thus the nanocomposite shows excellent PDT/photothermal therapy(PTT)synergistic performance in vitro and in vivo.展开更多
基金supported by the National Natural Science Foundation of China (No.21473167 and No.21688102)the National Key Research and Development Program of China (No.2016YFA0200604)+1 种基金the Fundamental Research Funds for the Central Universities (WK3430000005,WK2340000065)the China Scholarship Council (CSC) (No.201706345015)
文摘Based on density functional theory calculations,the full hydrolysis of per NH3BH3 molecule to produce three hydrogen molecules on single Pt atoms supported on oxidized graphene(Pt1/Gr-O)is investigated.It is suggested that the first hydrogen molecule is produced by the combination of two hydrogen atoms from two successive B-H bonds breaking.Then one H2O molecule attacks the left*BHNH3 group(*represents adsorbed state)to form*BH(H2O)NH3 and the elongated O-H bond is easily broken to produce*BH(OH)NH3.The second H2O molecule attacks*BH(OH)NH3 to form*BH(OH)(H2O)NH3 and the breaking of O-H bond pointing to the plane of Pt1/Gr-O results in the desorption of BH(OH)2NH3.The second hydrogen molecule is produced from two hydrogen atoms coming from two H2O molecules and Pt1/Gr-O is recovered after the releasing of hydrogen molecule.The third hydrogen molecule is generated by the further hydrolysis of BH(OH)2NH3 in water solution.The rate-limiting step of the whole process is the combination of one H2O molecule and*BHNH3 with an energy barrier of 16.1 kcal/mol.Thus,Pt1/Gr-O is suggested to be a promising catalyst for hydrolysis of NH3BH3 at room temperature.
基金funded by Ministerio de Ciencia e Innovación (Spain) (PID2019-105653GB-I00)Generalitat Valenciana (Spain) (PROMETEO/2020/063)。
文摘The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.
基金the National Natural Science Foundation of China(51872263 and 31970755)Zhejiang Provincial Natural Science Foundation(LZ19E020001 and LQ18B010002)。
文摘The hypoxic nature of solid tumors has severely negative effects on oxygen-based photodynamic therapy.In this study,we used porous Pt nanoparticles as a catalase(CAT)nanozyme,the second near-infrared(NIR-Ⅱ)region photothermal transition agents(PTAs),and carriers of photosensitizer chlorin e6(Ce6)to synthesize a composite nanosystem Pt-Ce6.In this system,Pt-Ce6 can continuously and stably decompose H2O2 into oxygen,thereby alleviating tumor hypoxia and improving the effect of photodynamic therapy(PDT).With 650 nm illumination,the reactive oxygen species(ROS)produced by Ce6 will decrease the mitochondrial membrane potential(MMP,ΔΨm)to release cytochrome c(Cyt-c)from the mitochondria into the cytoplasm,eventually leading to mitochondrial-mediated cellular apoptosis during the PDT process.In addition,Pt-Ce6 has good photothermal stability and high photothermal conversion efficiency(52.62%)in the NIR-II region.In U14 tumor-bearing mice,Pt-Ce6 completely suppressed tumor growth and recurrence under laser irradiation.Thus the nanocomposite shows excellent PDT/photothermal therapy(PTT)synergistic performance in vitro and in vivo.
