Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,...Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,carbon nitride(CN),still suffers from the drawbacks of narrow light absorption range and fast charge recombination.Here,we report a facile method to introduce nitrogen defects into carbon nitride together with sodium ion.By adjusting the ratio of sodium dicyandiamide,the band gap of carbon nitride can be controlled,while the carrier separation and transfer ability of carbon nitride is improved.The modified CN with sodium doping and nitrogen defect(SD-CN)demonstrates outstanding H_(2)O_(2)pro-duction performance(H_(2)O_(2)yield rate of 297.2μmol L^(−1)h^(−1))under visible light irradiation,which is approximately 9.8 times higher than that of pristine CN.This work deepens the understanding of the coordinated effect of structural defect and element doping of carbon nitride on the photocatalytic H_(2)O_(2)production performance,and provides new insight into the design of photocatalytic system for efficient production of H_(2)O_(2).展开更多
Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni（OH）2 upon aging in a s...Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni（OH）2 upon aging in a strong alkaline solution. In this study, the Al-Co, Al-Yb, Yb-Co and Al-Yb-Co multiple doping was used respectively. By controlling the amount of sodium carbonate, the α-Ni（OH）2 was prepared by ultrasonic-assisted precipitation. And the influence of sodium carbonate on the crystalline phase and structure stability for alpha nickel hydroxide was studied. The results demonstrate that, with increasing amount, the biphase nickel hydroxide transforms to pure alpha nickel hydroxide gradually, and the structure stability is also improved. When the amount of sodium carbonate is 2 g, the sample still keeps α-Ni（OH）2 after being aged for 30 days, for Al-Yb-Co-Ni（OH）2. And when the amount is less than 2 g, the phase transformations exist in the samples with different extents. These results demonstrated that the amount of sodium carbonate is a critical factor to maintain the structural stability of α-Ni（OH）2.展开更多
In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor film...In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor films by spin-coating NaCl solution.In subsequent selenization process,the introduction of Na Cl is found to be benefacial for the formation of Cu2-xSe,which can further facilitate the element transportation,leading to dense and smooth CZTSSe films with large grains and less impurity Cu2Sn(S,Se)3phase.SIMS depth profiles confirm the gradient distribution of the sodium element in Na-doped absorbers.Photoluminescence spectra show that the introduction of appropriate sodium into the absorber can inhibit the band tail states.As high as 11.18% of power conversion efficiency(PCE)is achieved for the device treated with 5 mg mL^-1 NaCl solution,and an average efficiency of Na-doped devices is 10.71%,13%higher than that of the control groups(9.45%).Besides,the depletion width and the charge recombination lifetime can also have regular variation with sodium treatment.This work offers an easy modification method for high-quality Na-doped CZTSSe films and high-performance devices,in the meantime,it can also help to further understand the effects of sodium in CZTSSe solar cells.展开更多
Nd∶NBW laser crystal with the size of Φ8 mm×20 mm was grown by the process of lifting and pulling. The growth technological parameters which have influence on the completeness of crystal were analyzed and the r...Nd∶NBW laser crystal with the size of Φ8 mm×20 mm was grown by the process of lifting and pulling. The growth technological parameters which have influence on the completeness of crystal were analyzed and the reasonable technological parameters were ascertained.展开更多
The separation of C_(2)H_(2)/C_(2)H_(4) mixtures is of industrial importance in the production of high-purity C_(2)H_(4) and C_(2)H_(2).The primary objective of this work is to enhance the selectivity of C_(2)H_(2)/C_...The separation of C_(2)H_(2)/C_(2)H_(4) mixtures is of industrial importance in the production of high-purity C_(2)H_(4) and C_(2)H_(2).The primary objective of this work is to enhance the selectivity of C_(2)H_(2)/C_(2)H_(4) separation by developing a method for appropriate modification of porous adsorbents.Toward this end,directly doping low-content Na+ions into covalent organic frameworks(COFs)via cation exchange is proposed in this work.Relative to the pristine COF,COF-ECUT-1,with C_(2)H_(2) and C_(2)H_(4) adsorption capacities of 55.39 cm^(3) g^(-1) and 28.63 cm^(3) g^(-1),the Na+-anchored phase with just 4.0 wt%sodium content,Na@COF-ECUT-1,enables largely enhanced adsorption ability with the corresponding values of 89.70 cm^(3) g^(-1) and 49.26 cm^(3) g^(-1),respectively.As a result,the adsorption selectivity of C_(2)H_(2) over that of C_(2)H_(4) is enhanced from 6.33 to 9.41,and the separation potential estimated by the simulated transient breakthrough is largely improved about three-fold.The density functional theory(DFT)calculation reveals that the trap of Na+within the COF channel affords strong affinity towards C_(2)H_(2) or C_(2)H_(4) through Na-πinteractions and relatively stronger contact for C_(2)H_(2) than for C_(2)H_(4) is observed.This result is in line with the experimental results of both enhanced C_(2)H_(2) and C_(2)H_(4) adsorption capacity and C_(2)H_(2)/C_(2)H_(4) separation performance.This work outlines a general and simple method to enhance the gas separation performance upon COF materials.展开更多
基金supported by the National Natural Science Foundation of China(No.22376159)the Fundamental Research Funds for the Central Universities(No.2022-4-ZD-08).
文摘Photocatalytic synthesis of hydrogen peroxide has gradually become a promising method for in-situ pro-duction of hydrogen peroxide,which relies on sustainable solar energy.However,the commonly used photocatalyst,i.e.,carbon nitride(CN),still suffers from the drawbacks of narrow light absorption range and fast charge recombination.Here,we report a facile method to introduce nitrogen defects into carbon nitride together with sodium ion.By adjusting the ratio of sodium dicyandiamide,the band gap of carbon nitride can be controlled,while the carrier separation and transfer ability of carbon nitride is improved.The modified CN with sodium doping and nitrogen defect(SD-CN)demonstrates outstanding H_(2)O_(2)pro-duction performance(H_(2)O_(2)yield rate of 297.2μmol L^(−1)h^(−1))under visible light irradiation,which is approximately 9.8 times higher than that of pristine CN.This work deepens the understanding of the coordinated effect of structural defect and element doping of carbon nitride on the photocatalytic H_(2)O_(2)production performance,and provides new insight into the design of photocatalytic system for efficient production of H_(2)O_(2).
基金Funded by the National Natural Science Foundation of China(No.51604087)the Science and Technology Program of Guangdong Province of China(No.2016A010104019)the Science and Technology Program of Guangzhou City of China(No.201607010001)
文摘Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni（OH）2 upon aging in a strong alkaline solution. In this study, the Al-Co, Al-Yb, Yb-Co and Al-Yb-Co multiple doping was used respectively. By controlling the amount of sodium carbonate, the α-Ni（OH）2 was prepared by ultrasonic-assisted precipitation. And the influence of sodium carbonate on the crystalline phase and structure stability for alpha nickel hydroxide was studied. The results demonstrate that, with increasing amount, the biphase nickel hydroxide transforms to pure alpha nickel hydroxide gradually, and the structure stability is also improved. When the amount of sodium carbonate is 2 g, the sample still keeps α-Ni（OH）2 after being aged for 30 days, for Al-Yb-Co-Ni（OH）2. And when the amount is less than 2 g, the phase transformations exist in the samples with different extents. These results demonstrated that the amount of sodium carbonate is a critical factor to maintain the structural stability of α-Ni（OH）2.
基金financially supported by the National Natural Science Foundation of China (Nos. 51421002, 51627803, 91733301, 51761145042, 21501183, 51402348, 53872321, and 11874402)the Knowledge Innovation Program and the Strategic Priority Research Program (Grant XDB 12010400) of the Chinese Academy of Sciences
文摘In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor films by spin-coating NaCl solution.In subsequent selenization process,the introduction of Na Cl is found to be benefacial for the formation of Cu2-xSe,which can further facilitate the element transportation,leading to dense and smooth CZTSSe films with large grains and less impurity Cu2Sn(S,Se)3phase.SIMS depth profiles confirm the gradient distribution of the sodium element in Na-doped absorbers.Photoluminescence spectra show that the introduction of appropriate sodium into the absorber can inhibit the band tail states.As high as 11.18% of power conversion efficiency(PCE)is achieved for the device treated with 5 mg mL^-1 NaCl solution,and an average efficiency of Na-doped devices is 10.71%,13%higher than that of the control groups(9.45%).Besides,the depletion width and the charge recombination lifetime can also have regular variation with sodium treatment.This work offers an easy modification method for high-quality Na-doped CZTSSe films and high-performance devices,in the meantime,it can also help to further understand the effects of sodium in CZTSSe solar cells.
文摘Nd∶NBW laser crystal with the size of Φ8 mm×20 mm was grown by the process of lifting and pulling. The growth technological parameters which have influence on the completeness of crystal were analyzed and the reasonable technological parameters were ascertained.
基金National Science Foundations of China(21871047 and 21661001)the Natural Science Foundation of Jiangxi Province of China(20181ACB20003).
文摘The separation of C_(2)H_(2)/C_(2)H_(4) mixtures is of industrial importance in the production of high-purity C_(2)H_(4) and C_(2)H_(2).The primary objective of this work is to enhance the selectivity of C_(2)H_(2)/C_(2)H_(4) separation by developing a method for appropriate modification of porous adsorbents.Toward this end,directly doping low-content Na+ions into covalent organic frameworks(COFs)via cation exchange is proposed in this work.Relative to the pristine COF,COF-ECUT-1,with C_(2)H_(2) and C_(2)H_(4) adsorption capacities of 55.39 cm^(3) g^(-1) and 28.63 cm^(3) g^(-1),the Na+-anchored phase with just 4.0 wt%sodium content,Na@COF-ECUT-1,enables largely enhanced adsorption ability with the corresponding values of 89.70 cm^(3) g^(-1) and 49.26 cm^(3) g^(-1),respectively.As a result,the adsorption selectivity of C_(2)H_(2) over that of C_(2)H_(4) is enhanced from 6.33 to 9.41,and the separation potential estimated by the simulated transient breakthrough is largely improved about three-fold.The density functional theory(DFT)calculation reveals that the trap of Na+within the COF channel affords strong affinity towards C_(2)H_(2) or C_(2)H_(4) through Na-πinteractions and relatively stronger contact for C_(2)H_(2) than for C_(2)H_(4) is observed.This result is in line with the experimental results of both enhanced C_(2)H_(2) and C_(2)H_(4) adsorption capacity and C_(2)H_(2)/C_(2)H_(4) separation performance.This work outlines a general and simple method to enhance the gas separation performance upon COF materials.
