p-n heterostructure(HTS) is a fundamental component for high-performance electronic and optoelectronic device. Vertical stacking through van der Waals(vdW) force is emerging as a feasible technique to construct p-n HT...p-n heterostructure(HTS) is a fundamental component for high-performance electronic and optoelectronic device. Vertical stacking through van der Waals(vdW) force is emerging as a feasible technique to construct p-n HTS. Herein, we designed a novel kind of direct-bandgap C_3N monolayer, via adjusting the arrangement of C and N atoms in C_3N hexagonal cell. On the basis of the density functional theory combined with the non-equilibrium Green's function method, we built two-dimensional vdW-contact phosphorene(BP)/C_3N p-n HTS, and analyzed its electronic and optical properties in comparison with the inplanejointed ones. The strong charge transfer between BP and C_3N segments results in a wide bandgap of 0.48 eV for joint-contact type BP/C_3N HTS, whereas the effective interlayer coupling in vdW-contact type leads to an improved light adsorption as compared to the isolated C_3N monolayer. By fabricating dual-gated BP/C_3N HTS field-effect transistors(FETs), the dynamic transport behaviors demonstrated that the band bending under a lower threshold voltage makes band-to-band tunneling possible for vdW-contact type. Our work suggests that vdW-contact type is superior to joint-contact type in constructing p-n HTS for high-performance electronic and optoelectronic devices.展开更多
Linear relations between the adsorption free energies of nitrogen reduction reaction(NRR)intermediates limit the catalytic activity of single atom catalysts(SACs)to reach the optimal region.Significant improvements in...Linear relations between the adsorption free energies of nitrogen reduction reaction(NRR)intermediates limit the catalytic activity of single atom catalysts(SACs)to reach the optimal region.Significant improvements in NRR activity require the balance of binding strength of reaction intermediates.Herein,we have investigated the C_(3)N-supported monometallic(M/C_(3)N)and bimetallic(M_(1)M_(2)/C_(3)N)atoms for the electrochemical NRR by using density functional theory(DFT)calculations.The results show that this linear relation does exist for SACs because all the intermediates bind to the same site on M/C_(3)N.But the synergistic effect of the two atoms in M_(1)M_(2)/C_(3)N can create a more flexible adsorption site for intermediates,which results in the decoupling of adsorption free energies of key intermediates.Subsequently,the fundamental limitation of scaling relations on limiting potentials is broken through.Most notably,the optimal limiting potential is increased from−0.63 V for M/C_(3)N to−0.20 V for M_(1)M_(2)/C_(3)N.In addition,the presence of bimetallic atoms can also effectively inhibit the hydrogen evolution reaction(HER)as well as improve the stability of the catalysts.This study proposes that the introduction of bimetallic atoms into C_(3)N is beneficial to break the linear relations and develop efficient NRR electrocatalysts.展开更多
As a two-dimensional carbon based semiconductor,C_(3)N acts as a promising material in many application areas.However,the basic physical properties such as Raman spectrum properties of C_(3)N is still not clear.In thi...As a two-dimensional carbon based semiconductor,C_(3)N acts as a promising material in many application areas.However,the basic physical properties such as Raman spectrum properties of C_(3)N is still not clear.In this paper,we clarify the Raman spectrum properties of multilayer C_(3)N.Moreover,the stacking driven Raman spectra change of multilayer C_(3)N is also discussed.展开更多
The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temper...The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temperature region for the present compound. Theresults have been compared with those reported in [1] in the overlapping temperaturerange. The experimental heat capacity data have been fitted to a smoothed curve by the aidof the effective frequency distribution method, and the heat capacities below 13K have beenobtained by extrapolating the fitting curve down to 0K. The standard molar thermodynamicfunctions between 0 and 400 K have been derived by combining the present heat capacitymeasurements with the previous ones. The values of C_p^o (T), S^o(T) - S^o(0), [H^o(T) -H^o(0)]/T, and - [G^o(T) - H^o(0)]/T at T = 298.15 K are 189.35, 244.60, 112 .45 and 132.15J·K^(-1)·mol^(-1), respectively.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.1180424251802121 and 51861145202)+3 种基金the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ18E040001)the Jiangsu Provincial Natural Science Funding Project(Grant No.BK20160308)the Jiaxing Science and Technology Project(Grant No.2017AY13009)the 111 Program
文摘p-n heterostructure(HTS) is a fundamental component for high-performance electronic and optoelectronic device. Vertical stacking through van der Waals(vdW) force is emerging as a feasible technique to construct p-n HTS. Herein, we designed a novel kind of direct-bandgap C_3N monolayer, via adjusting the arrangement of C and N atoms in C_3N hexagonal cell. On the basis of the density functional theory combined with the non-equilibrium Green's function method, we built two-dimensional vdW-contact phosphorene(BP)/C_3N p-n HTS, and analyzed its electronic and optical properties in comparison with the inplanejointed ones. The strong charge transfer between BP and C_3N segments results in a wide bandgap of 0.48 eV for joint-contact type BP/C_3N HTS, whereas the effective interlayer coupling in vdW-contact type leads to an improved light adsorption as compared to the isolated C_3N monolayer. By fabricating dual-gated BP/C_3N HTS field-effect transistors(FETs), the dynamic transport behaviors demonstrated that the band bending under a lower threshold voltage makes band-to-band tunneling possible for vdW-contact type. Our work suggests that vdW-contact type is superior to joint-contact type in constructing p-n HTS for high-performance electronic and optoelectronic devices.
文摘Linear relations between the adsorption free energies of nitrogen reduction reaction(NRR)intermediates limit the catalytic activity of single atom catalysts(SACs)to reach the optimal region.Significant improvements in NRR activity require the balance of binding strength of reaction intermediates.Herein,we have investigated the C_(3)N-supported monometallic(M/C_(3)N)and bimetallic(M_(1)M_(2)/C_(3)N)atoms for the electrochemical NRR by using density functional theory(DFT)calculations.The results show that this linear relation does exist for SACs because all the intermediates bind to the same site on M/C_(3)N.But the synergistic effect of the two atoms in M_(1)M_(2)/C_(3)N can create a more flexible adsorption site for intermediates,which results in the decoupling of adsorption free energies of key intermediates.Subsequently,the fundamental limitation of scaling relations on limiting potentials is broken through.Most notably,the optimal limiting potential is increased from−0.63 V for M/C_(3)N to−0.20 V for M_(1)M_(2)/C_(3)N.In addition,the presence of bimetallic atoms can also effectively inhibit the hydrogen evolution reaction(HER)as well as improve the stability of the catalysts.This study proposes that the introduction of bimetallic atoms into C_(3)N is beneficial to break the linear relations and develop efficient NRR electrocatalysts.
基金supported by The National Natural Science Foundation of China (Nos. 11804353 and 11774368)Shanghai Science and Technology Committee (No. 18511110600)
文摘As a two-dimensional carbon based semiconductor,C_(3)N acts as a promising material in many application areas.However,the basic physical properties such as Raman spectrum properties of C_(3)N is still not clear.In this paper,we clarify the Raman spectrum properties of multilayer C_(3)N.Moreover,the stacking driven Raman spectra change of multilayer C_(3)N is also discussed.
文摘The heat capacity of 2- chloro- 6- (trichloromethyl)pyridine has heen measured with anadiabatic calorimeter in the range from 13 to 316K. There is no indication of any phasetransition or thermal anomaly in this temperature region for the present compound. Theresults have been compared with those reported in [1] in the overlapping temperaturerange. The experimental heat capacity data have been fitted to a smoothed curve by the aidof the effective frequency distribution method, and the heat capacities below 13K have beenobtained by extrapolating the fitting curve down to 0K. The standard molar thermodynamicfunctions between 0 and 400 K have been derived by combining the present heat capacitymeasurements with the previous ones. The values of C_p^o (T), S^o(T) - S^o(0), [H^o(T) -H^o(0)]/T, and - [G^o(T) - H^o(0)]/T at T = 298.15 K are 189.35, 244.60, 112 .45 and 132.15J·K^(-1)·mol^(-1), respectively.
