The preparation and application of supported gold and copper catalysts are fundamentally and practically very important.Herein,we confirm that the Au-Cu promoted In_(2)O_(3) catalyst demonstrates a significant electro...The preparation and application of supported gold and copper catalysts are fundamentally and practically very important.Herein,we confirm that the Au-Cu promoted In_(2)O_(3) catalyst demonstrates a significant electronic metal-support interaction(EMSI),which plays a critical role in CO_(2) hydrogenation to methanol and leads to significantly improved activity,compared to the mono-metallic Au and Cu promoted In_(2)O_(3)catalysts.This interaction arises from electron transfer between the oxygen deficient In_(2)O_(3) support and the bimetallic clusters,rendering both Au and Cu clusters positively charged.The presence of Cu^(3+)stabilizes and optimizes the content of oxygen vacancies,leading to a more pronounced positive charge on Au clusters(Au^(3+)).The ability to activate H_(2) is thus enhanced.CO adsorption on Au-Cu/In_(2)O_(3) is also stronger than Au/In_(2)O_(3).This results in higher methanol selectivity of Au-Cu/In_(2)O_(3),with which CO hydrogenation pathway is taken for CO_(2) hydrogenation to methanol.The enhanced H_(2) activation and stronger CO adsorption over Au-Cu/In_(2)O_(3) are key factors in boosting the activity for methanol formation from CO_(2)hvdrogenation.展开更多
Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrins...Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrinsic electronic structure with d-orbitals fully filled, thus limiting the activation and reduction of CO_(2). To address this issue and maximize the photoreduction of CO_(2), herein we have designed Au@CZS@MO-400 triple-shelled hollow nanospheres by depositing Cd_(0.7)Zn_(0.3)S (CZS) on the outer surface of the MO-400 (MnO_(2) annealed at 400 ℃) hollow nanospheres and then Au nanoparticles on the CZS surface. It is manifested that the resultant 3%Au@CZS@MO-400 achieves a remarkably boosted photoreduction of CO_(2) with the CO/CH_(4) yield rates as high as 68.25/12.42 µmol g^(-1) h^(-1), increased by 3.7/1.5 times over MO-400 and 12.9/1.5 times over CZS. The combined analyses from X-ray photoelectron spectroscopy and density functional theory calculations confirm the creation of electron-deficient Auδ+ active sites by modulating their electron configuration by CZS, consequently decreasing the CO_(2)-Au antibonding-orbital occupancy to reinforce the adsorption strength of CO_(2) onto the Au active sites and in turn boost the photoreduction of CO_(2). Moreover, it is demonstrated that the Au@CZS@MO-400 hollow nanospheres are quite efficient for supplying the Au cocatalyst with photoelectrons for CO_(2) reduction reactions due to the good energy band matching, unique hollow structure and high electron spin polarization of MO-400. This work provides important guidance for understanding and modifying photocatalysts to maximize their photoreduction of CO_(2).展开更多
Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE...Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.展开更多
基金supported by the National Natural Science Foundation of China(22138009)the Fundamental Research Funds for the Central Universities of China。
文摘The preparation and application of supported gold and copper catalysts are fundamentally and practically very important.Herein,we confirm that the Au-Cu promoted In_(2)O_(3) catalyst demonstrates a significant electronic metal-support interaction(EMSI),which plays a critical role in CO_(2) hydrogenation to methanol and leads to significantly improved activity,compared to the mono-metallic Au and Cu promoted In_(2)O_(3)catalysts.This interaction arises from electron transfer between the oxygen deficient In_(2)O_(3) support and the bimetallic clusters,rendering both Au and Cu clusters positively charged.The presence of Cu^(3+)stabilizes and optimizes the content of oxygen vacancies,leading to a more pronounced positive charge on Au clusters(Au^(3+)).The ability to activate H_(2) is thus enhanced.CO adsorption on Au-Cu/In_(2)O_(3) is also stronger than Au/In_(2)O_(3).This results in higher methanol selectivity of Au-Cu/In_(2)O_(3),with which CO hydrogenation pathway is taken for CO_(2) hydrogenation to methanol.The enhanced H_(2) activation and stronger CO adsorption over Au-Cu/In_(2)O_(3) are key factors in boosting the activity for methanol formation from CO_(2)hvdrogenation.
基金supported by the Gansu Province Outstanding PhD Student Fund(No.24JRRA206)the National Natural Sci-ence Foundation of China(No.52162040).
文摘Recently, the noble metal Au has been widely applied as the cocatalyst for improving the photocatalytic reduction of CO_(2). However, the metallic Au exhibits weak adsorption strength towards CO_(2) due to its intrinsic electronic structure with d-orbitals fully filled, thus limiting the activation and reduction of CO_(2). To address this issue and maximize the photoreduction of CO_(2), herein we have designed Au@CZS@MO-400 triple-shelled hollow nanospheres by depositing Cd_(0.7)Zn_(0.3)S (CZS) on the outer surface of the MO-400 (MnO_(2) annealed at 400 ℃) hollow nanospheres and then Au nanoparticles on the CZS surface. It is manifested that the resultant 3%Au@CZS@MO-400 achieves a remarkably boosted photoreduction of CO_(2) with the CO/CH_(4) yield rates as high as 68.25/12.42 µmol g^(-1) h^(-1), increased by 3.7/1.5 times over MO-400 and 12.9/1.5 times over CZS. The combined analyses from X-ray photoelectron spectroscopy and density functional theory calculations confirm the creation of electron-deficient Auδ+ active sites by modulating their electron configuration by CZS, consequently decreasing the CO_(2)-Au antibonding-orbital occupancy to reinforce the adsorption strength of CO_(2) onto the Au active sites and in turn boost the photoreduction of CO_(2). Moreover, it is demonstrated that the Au@CZS@MO-400 hollow nanospheres are quite efficient for supplying the Au cocatalyst with photoelectrons for CO_(2) reduction reactions due to the good energy band matching, unique hollow structure and high electron spin polarization of MO-400. This work provides important guidance for understanding and modifying photocatalysts to maximize their photoreduction of CO_(2).
基金Project(2022YFB3707201) supported by the National Key R&D Program of ChinaProject(U2341254) supported by the Ye Qisun Science Foundation of National Natural Science Foundation of China+1 种基金Projects(0604022GH0202143,0604022SH0201143) supported by the NPU Aoxiang Distinguished Young Scholars,ChinaProject supported by the Funding of Young Top-notch Talent of the National Ten Thousand Talent Program,China。
文摘Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.
