A kind of solar thermochemical cycle based on methanothermal reduction of SnO2 is proposed for H2 and CO production. We find that the oxygen release capacity and thermodynamic driven force for methanothermal reduction...A kind of solar thermochemical cycle based on methanothermal reduction of SnO2 is proposed for H2 and CO production. We find that the oxygen release capacity and thermodynamic driven force for methanothermal reduction of SnO2 are large, and suggest CH4 :SnO2 = 2:1 as the feasible reduction condition for achieving high purities of syngas and avoiding vaporization of produced Sn. Subsequently, the amount of H2 and energetic upgrade factors under different oxidation conditions are compared, in which excess water vapor is found beneficial for hydrogen production and fuel energetic upgradation. Moreover, the effect of incom plete recovery of SnO2 on the subsequent cycle is underscored and explained. After accounting for factors such as isothermal operation and cycle stability, CH4 :SnO2 = 2:1 and H2O:Sn = 4:1 are suggested for highest solar-to-fuel efficiency of 46.1% at nonisothermal condition, where the reduction and oxidation temperature are 1400 and 600 K, respectively.展开更多
Inspired by the promising hydrogen production in the solar thermochemical(STC)cycle based on non-stoichiometric oxides and the operation temperature decreasing effect of methane reduction,a high-fuel-selectivity and C...Inspired by the promising hydrogen production in the solar thermochemical(STC)cycle based on non-stoichiometric oxides and the operation temperature decreasing effect of methane reduction,a high-fuel-selectivity and CH4-introduced solar thermochemical cycle based on MoO2/Mo is studied.By performing HSC simulations,the energy upgradation and energy conversion potential under isothermal and non-isothermal operating conditions are compared.In the reduction step,MoO2:CH4=2 and 1020 K<Tred<1600 K are found to be most favorable for syngas selectivity and methane conversion.Compared to the STC cycle without CH4,the introduction of methane yields a much higher hydrogen production,especially at the lower temperature range and atmospheric pressure.In the oxidation step,a moderately excessive water is beneficial for energy conversion whether in isothermal or non-isothermal operations,especially at H2O:Mo=4.In the whole STC cycle,the maximum non-isothermal and isothermal efficiency can reach 0.417 and 0.391 respectively.In addition,the predicted efficiency of the second cycle is also as high as 0.454 at Tred=1200 K and Toxi=400 K,indicating that MoO2 could be a new and potential candidate for obtaining solar fuel by methane reduction.展开更多
Highly reducible and thermally stable lanthanum-manganese perovskites represent a promising class of materials for solar thermochemical hydrogen production.However,such materials suffer from a low hydrogen production ...Highly reducible and thermally stable lanthanum-manganese perovskites represent a promising class of materials for solar thermochemical hydrogen production.However,such materials suffer from a low hydrogen production rate,resulting in an incomplete re-oxidation yield.To enhance the kinetic performance,the mechanism of water-splitting and hydrogen production around the oxygen vacancy of the LaMnO_(3)(010)defective surface is revealed.A transition state with the activation energy E_(a)=126.45 kJ mol^(-1)is explored in the rate-determining step of hydrogen transfer from superficial O to neighbor Mn.Based on the analysis of the E_(a)results,the H_(2)production time ratio between La_(0.9)Sr_(0.4)MnO_(3)and La_(0.9)Sr_(0.1)MnO_(3)is 47.3,close to the experimental data from the literature.Also,the kinetic unfavourability of Sr and the favorability of Al and Ga are predicted,which are in good agreement with previous experimental phenomena.Moreover,La_(0.875)Sr_(0.125)Mn_(0.875)Mo_(0.125)O_(3)is suggested as a promising material to rapidly produce H_(2).All the results demonstrate the effectiveness of the proposed water-splitting mechanism and provide an easy access for fast determination of kinetically favorable dopants for lanthanum-strontium-manganese perovskites.展开更多
Solar thermochemical water-splitting(STWS)via a two-step redox reaction is a promising H_(2)production technique,but the quantity and performance limitations of perovskite materials motivate the discovery of novel hig...Solar thermochemical water-splitting(STWS)via a two-step redox reaction is a promising H_(2)production technique,but the quantity and performance limitations of perovskite materials motivate the discovery of novel high-performance candidates.Through oxygen vacancy-driven water-splitting mechanism analysis and doping-mixture modification,a Cr-perovskite is designed for STWS cycling.展开更多
An efficient prediction procedure is designed for the quick screening of solar thermochemical (STC) perovskites for H_(2) production.The core classifier is based on the random forest method,and the input information i...An efficient prediction procedure is designed for the quick screening of solar thermochemical (STC) perovskites for H_(2) production.The core classifier is based on the random forest method,and the input information is easily accessible from chemical formula and periodic table.For ABO_(3)-type perovskites,the prediction accuracy is high even within a small number of training samples.The prominent feature of the program is the fast and accurate identification of doped perovskites,which is almost impossible when studied individually by experimental and density functional theory methods.By using more than 380 ABO_(3) as train samples,a stable accuracy of more than 90% is obtained,which is much larger than the results of probabilistic neutral network and exact radial basis network methods.All the results demonstrated the effectiveness of prediction procedure and provided a valuable reference for high throughput exploration in fields other than STC H_(2) production.展开更多
基金supported by the National Key R&D Program of China (Grant no. 2018YFB1502005)the National Natural Science Foundation of China (Grant nos. 51476163 , 51806209 and 81801768)Institute of Electrical Engineering, Chinese Academy of Sciences (No.Y770111CSC)
文摘A kind of solar thermochemical cycle based on methanothermal reduction of SnO2 is proposed for H2 and CO production. We find that the oxygen release capacity and thermodynamic driven force for methanothermal reduction of SnO2 are large, and suggest CH4 :SnO2 = 2:1 as the feasible reduction condition for achieving high purities of syngas and avoiding vaporization of produced Sn. Subsequently, the amount of H2 and energetic upgrade factors under different oxidation conditions are compared, in which excess water vapor is found beneficial for hydrogen production and fuel energetic upgradation. Moreover, the effect of incom plete recovery of SnO2 on the subsequent cycle is underscored and explained. After accounting for factors such as isothermal operation and cycle stability, CH4 :SnO2 = 2:1 and H2O:Sn = 4:1 are suggested for highest solar-to-fuel efficiency of 46.1% at nonisothermal condition, where the reduction and oxidation temperature are 1400 and 600 K, respectively.
基金supported by the Innovation Practice Training Program of College Students,Chinese Academy of Sciences(Application No.20184000028)the Practical Training Program of Beijing University of Higher Education High-level Talents Cross-cultivation(No.16053225)the National Natural Science Foundation of China(Grant Nos.51476163,51806209 and 81801768).
文摘Inspired by the promising hydrogen production in the solar thermochemical(STC)cycle based on non-stoichiometric oxides and the operation temperature decreasing effect of methane reduction,a high-fuel-selectivity and CH4-introduced solar thermochemical cycle based on MoO2/Mo is studied.By performing HSC simulations,the energy upgradation and energy conversion potential under isothermal and non-isothermal operating conditions are compared.In the reduction step,MoO2:CH4=2 and 1020 K<Tred<1600 K are found to be most favorable for syngas selectivity and methane conversion.Compared to the STC cycle without CH4,the introduction of methane yields a much higher hydrogen production,especially at the lower temperature range and atmospheric pressure.In the oxidation step,a moderately excessive water is beneficial for energy conversion whether in isothermal or non-isothermal operations,especially at H2O:Mo=4.In the whole STC cycle,the maximum non-isothermal and isothermal efficiency can reach 0.417 and 0.391 respectively.In addition,the predicted efficiency of the second cycle is also as high as 0.454 at Tred=1200 K and Toxi=400 K,indicating that MoO2 could be a new and potential candidate for obtaining solar fuel by methane reduction.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB1502005)the National Natural Science Foundation of China(Grant No.51806209 and 81801768)the Institute of Electrical Engineering,Chinese Academy of Sciences(No.Y770111CSC).
文摘Highly reducible and thermally stable lanthanum-manganese perovskites represent a promising class of materials for solar thermochemical hydrogen production.However,such materials suffer from a low hydrogen production rate,resulting in an incomplete re-oxidation yield.To enhance the kinetic performance,the mechanism of water-splitting and hydrogen production around the oxygen vacancy of the LaMnO_(3)(010)defective surface is revealed.A transition state with the activation energy E_(a)=126.45 kJ mol^(-1)is explored in the rate-determining step of hydrogen transfer from superficial O to neighbor Mn.Based on the analysis of the E_(a)results,the H_(2)production time ratio between La_(0.9)Sr_(0.4)MnO_(3)and La_(0.9)Sr_(0.1)MnO_(3)is 47.3,close to the experimental data from the literature.Also,the kinetic unfavourability of Sr and the favorability of Al and Ga are predicted,which are in good agreement with previous experimental phenomena.Moreover,La_(0.875)Sr_(0.125)Mn_(0.875)Mo_(0.125)O_(3)is suggested as a promising material to rapidly produce H_(2).All the results demonstrate the effectiveness of the proposed water-splitting mechanism and provide an easy access for fast determination of kinetically favorable dopants for lanthanum-strontium-manganese perovskites.
基金supported by the National Key R&D Program of China(No.2021YFE0102800)the National Natural Science Foundation of China(Grant No.52176209)the International Partnership Program of Chinese Academy of Sciences(No.182111KYSB20200021).
文摘Solar thermochemical water-splitting(STWS)via a two-step redox reaction is a promising H_(2)production technique,but the quantity and performance limitations of perovskite materials motivate the discovery of novel high-performance candidates.Through oxygen vacancy-driven water-splitting mechanism analysis and doping-mixture modification,a Cr-perovskite is designed for STWS cycling.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB1502005)National Natural Science Foundation of China(Grant No.51806209)International Partnership Program of Chinese Academy of Sciences(182111KYSB20200021).
文摘An efficient prediction procedure is designed for the quick screening of solar thermochemical (STC) perovskites for H_(2) production.The core classifier is based on the random forest method,and the input information is easily accessible from chemical formula and periodic table.For ABO_(3)-type perovskites,the prediction accuracy is high even within a small number of training samples.The prominent feature of the program is the fast and accurate identification of doped perovskites,which is almost impossible when studied individually by experimental and density functional theory methods.By using more than 380 ABO_(3) as train samples,a stable accuracy of more than 90% is obtained,which is much larger than the results of probabilistic neutral network and exact radial basis network methods.All the results demonstrated the effectiveness of prediction procedure and provided a valuable reference for high throughput exploration in fields other than STC H_(2) production.
