Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as ...Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.展开更多
Enthalpy changes of the reactions involved in our previous papers have been re-examined at the G2(MP2) and G2 levels. The G2(MP2) and G2 energies of Ar, Ar+,ArAr+, ArCl+, ArF+, ArH+, ArHe+, ArNe+, ArO+, ArS+, H2+, He,...Enthalpy changes of the reactions involved in our previous papers have been re-examined at the G2(MP2) and G2 levels. The G2(MP2) and G2 energies of Ar, Ar+,ArAr+, ArCl+, ArF+, ArH+, ArHe+, ArNe+, ArO+, ArS+, H2+, He, HeCl+, HeF+, HeO+,HeS+, Ne, NeCl+, NeF+, NeO+ and NeS+ have been calculated. The G2(MP2) and G2 results for all of the interested reactions have also been compared with those of the previous MP2/6-31G** and MP4/6-311G (2df, 2pd) calculations. All of the G2(MP2) and G2 reaction enthalpies are improved from the MP2 and MP4 level of calculations when compared with the experimental data for the four categories of reactions as (1) iso-electronic, isogyric; (2) valence isoelectronic, isogyric; (3) isogyric and (4)non-isogyric reactions with the average absolute deviations of 5.10, 4.60, 7.70 and 9.20 for G2(MP2) and 4.18, 5.19, 6.78 and 6.49kJ·mol-1 for G2, respectively. The individural deviation for almost all of the reactions involved in this work is not more than±13kJ·mol-1 for G2(MP2) and ±8.4kJ·mol-1 for G2. In this paper, an additional number of reactions examined at the G2(MP2) and G2 levels as well as at the MP2/6-31G** and MP4/6-311G (2df, 2pd) levels of calculations have also been reported. The MP2, MP4, G2(MP2) and G2 total energies for the interested chemical species have been calculated if these energies have not been reported in literatures. All of the reaction energies at different levels have been compared with the experimental data in a nummber of reactions devided into the above four categories. The average absolute deviations are 25.9, 36.0, 29.2 and 40.1 for MP2; 8.41, 18.3, 17.2 and 18.3 for MP4; 9.41, 5.98, 4.85 and 6.90 for G2(MP2) and 6.69, 4.06, 3.85 and 4.60 kJ·mol-1 for G2, respectively. It is clear that the MP2 calculation did quite poor for all of the foux categories of reactions and the MP4 did well only for the isoelectronic and isogyric reactions. The G2(MP2) and G2 reproduce the eaperimental reaction enthalpy changes very well for all reactions in the four categories. The individural deviation for almost all of the reactions involved in this work is not more than ±13kJ·mol-1 for G2(MP2) and ±8.4kJ·mol-l for G2 while it may be more than ±84kJ·mol-1 for MP2/6-31G**.展开更多
The atomization energies for BeF, BeF2, BF, BF2, BF3, BO, CF and CF2;electronic affoties for B, BO, CF, Li and LiF; ionization potentials(IP1) for BeF, BF2, BO,CF, CF2, CN, NO and NO2, IP2 for C, N and CF have been ca...The atomization energies for BeF, BeF2, BF, BF2, BF3, BO, CF and CF2;electronic affoties for B, BO, CF, Li and LiF; ionization potentials(IP1) for BeF, BF2, BO,CF, CF2, CN, NO and NO2, IP2 for C, N and CF have been calculated at the G2(MP2) and G2 ab initio levels. These molecules are in their gaseous and ground electronic states with the temperature respect to 298K. The G2(MP2) results are compared with those of the G2 and the theoretical results are compared with those of the experiments as shown in Table 2 through Table 5. The G2(MP2) results for these 24 energies are in good agreement with those of the G2. Their deviations are within±10kJ·mol-1 and the average absolute deviation is 3.2kJ·mol-1. When compared with theories, the experimental results are in fairly agreement in most cases. For the larger deviations, we suppose that the experimental heat of formation for BeF is a little bit too low by about 10-20kJ.mol-1, the electronic affinities for B, BO, CF and LiF are suggested to be re-exandned, the experimental ionization potentials (IP1) for BeF, BF2 and CN are suggested to some further study and the IP2 for CF must be in error in the NBS Tables.展开更多
To study The MALDI-TOF- Mass Spectfometry of silver phenylacetylide in order to investigate The state of aggregation of The functionalized transition metal coordinated compounds including clusters and determine The de...To study The MALDI-TOF- Mass Spectfometry of silver phenylacetylide in order to investigate The state of aggregation of The functionalized transition metal coordinated compounds including clusters and determine The degree of ploymerization of the Silver phenylacetylide. Methods: The silver phenylacetylides were analyzed by The method of MALDI-TOF-MS. Results: The main members of The silver phenylacetylide were tetramer and pentamer The degree of polymerization was found to be up to twelve. Conclusion: The polymerization series of The silver phenylacetylide are according to The formula: Mn= nM+ Ag, (n = 1.2.3... ).展开更多
基金the National Basic Research Development of China(2011CB936003)the National Natural Science Foundation of China(50971116)。
文摘Photocatalytic splitting of water over p-type semiconductors is a promising strategy for production of hydrogen.However,the determination of rate law is rarely reported.To this purpose,copper oxide(CuO)is selected as a model photocathode in this study,and the photogenerated surface charge density,interfacial charge transfer rate constant and their relation to the water reduction rate(in terms of photocurrent)were investigated by a combination of(photo)electrochemical techniques.The results showed that the charge transfer rate constant is exponential-dependent on the surface charge density,and that the photocurrent equals to the product of the charge transfer rate constant and surface charge density.The reaction is first-order in terms of surface charge density.Such an unconventional rate law contrasts with the reports in literature.The charge density-dependent rate constant results from the Fermi level pinning(i.e.,Galvani potential is the main driving force for the reaction)due to accumulation of charge in the surface states and/or Frumkin behavior(i.e.,chemical potential is the main driving force).This study,therefore,may be helpful for further investigation on the mechanism of hydrogen evolution over a CuO photocathode and for designing more efficient CuO-based photocatalysts.
文摘Enthalpy changes of the reactions involved in our previous papers have been re-examined at the G2(MP2) and G2 levels. The G2(MP2) and G2 energies of Ar, Ar+,ArAr+, ArCl+, ArF+, ArH+, ArHe+, ArNe+, ArO+, ArS+, H2+, He, HeCl+, HeF+, HeO+,HeS+, Ne, NeCl+, NeF+, NeO+ and NeS+ have been calculated. The G2(MP2) and G2 results for all of the interested reactions have also been compared with those of the previous MP2/6-31G** and MP4/6-311G (2df, 2pd) calculations. All of the G2(MP2) and G2 reaction enthalpies are improved from the MP2 and MP4 level of calculations when compared with the experimental data for the four categories of reactions as (1) iso-electronic, isogyric; (2) valence isoelectronic, isogyric; (3) isogyric and (4)non-isogyric reactions with the average absolute deviations of 5.10, 4.60, 7.70 and 9.20 for G2(MP2) and 4.18, 5.19, 6.78 and 6.49kJ·mol-1 for G2, respectively. The individural deviation for almost all of the reactions involved in this work is not more than±13kJ·mol-1 for G2(MP2) and ±8.4kJ·mol-1 for G2. In this paper, an additional number of reactions examined at the G2(MP2) and G2 levels as well as at the MP2/6-31G** and MP4/6-311G (2df, 2pd) levels of calculations have also been reported. The MP2, MP4, G2(MP2) and G2 total energies for the interested chemical species have been calculated if these energies have not been reported in literatures. All of the reaction energies at different levels have been compared with the experimental data in a nummber of reactions devided into the above four categories. The average absolute deviations are 25.9, 36.0, 29.2 and 40.1 for MP2; 8.41, 18.3, 17.2 and 18.3 for MP4; 9.41, 5.98, 4.85 and 6.90 for G2(MP2) and 6.69, 4.06, 3.85 and 4.60 kJ·mol-1 for G2, respectively. It is clear that the MP2 calculation did quite poor for all of the foux categories of reactions and the MP4 did well only for the isoelectronic and isogyric reactions. The G2(MP2) and G2 reproduce the eaperimental reaction enthalpy changes very well for all reactions in the four categories. The individural deviation for almost all of the reactions involved in this work is not more than ±13kJ·mol-1 for G2(MP2) and ±8.4kJ·mol-l for G2 while it may be more than ±84kJ·mol-1 for MP2/6-31G**.
文摘The atomization energies for BeF, BeF2, BF, BF2, BF3, BO, CF and CF2;electronic affoties for B, BO, CF, Li and LiF; ionization potentials(IP1) for BeF, BF2, BO,CF, CF2, CN, NO and NO2, IP2 for C, N and CF have been calculated at the G2(MP2) and G2 ab initio levels. These molecules are in their gaseous and ground electronic states with the temperature respect to 298K. The G2(MP2) results are compared with those of the G2 and the theoretical results are compared with those of the experiments as shown in Table 2 through Table 5. The G2(MP2) results for these 24 energies are in good agreement with those of the G2. Their deviations are within±10kJ·mol-1 and the average absolute deviation is 3.2kJ·mol-1. When compared with theories, the experimental results are in fairly agreement in most cases. For the larger deviations, we suppose that the experimental heat of formation for BeF is a little bit too low by about 10-20kJ.mol-1, the electronic affinities for B, BO, CF and LiF are suggested to be re-exandned, the experimental ionization potentials (IP1) for BeF, BF2 and CN are suggested to some further study and the IP2 for CF must be in error in the NBS Tables.
文摘To study The MALDI-TOF- Mass Spectfometry of silver phenylacetylide in order to investigate The state of aggregation of The functionalized transition metal coordinated compounds including clusters and determine The degree of ploymerization of the Silver phenylacetylide. Methods: The silver phenylacetylides were analyzed by The method of MALDI-TOF-MS. Results: The main members of The silver phenylacetylide were tetramer and pentamer The degree of polymerization was found to be up to twelve. Conclusion: The polymerization series of The silver phenylacetylide are according to The formula: Mn= nM+ Ag, (n = 1.2.3... ).
