RESUMEN
Photothermal catalysis is a promising method for selectively oxidizing organic compounds, effectively addressing the energy-intensive and low-selective processes of thermal catalysis, as well as the slow reaction rates of photocatalysis. In this study, a ternary photothermal catalyst, Ni/CeO2/CdS, was synthesized using a simple calcination and solvothermal method. The catalyst demonstrated remarkable improvement in reaction rates and achieved nearly 100% selectivity in converting benzyl alcohol to benzaldehyde through photothermal catalysis at normal pressure. The reaction rates were 5.9 times and 63 times higher than those of CdS and Ni/CeO2 individually. XPS analysis confirmed that the thermal catalysis followed the Mars-Van Krevelen (MVK) mechanism and also proved that photocatalysis facilitated the MVK cycle. Additionally, DFT calculations showed that Ni acted as an electron transfer channel, facilitating efficient Z-scheme charge transfer. The in situ infrared technique was used to dynamically monitor the reaction process and explain the high selectivity of the product. Furthermore, detailed explanations of photocatalysis, thermocatalysis, and photothermal synergistic catalysis were proposed based on the aforementioned characterization and theoretical calculations. This approach establishes a theoretical foundation for the development of efficient photothermal catalysts.
RESUMEN
The sulfur/nitrogen co-doped activated carbon fiber (S/N-ACF) is prepared by the thermal treatment of thiourea-bonded hydroxyl-rich carbon fiber, which can bond the decomposition products of thiourea through hydrogen bond interaction to avoid the significant loss of sulfur and nitrogen sources during the thermal treatment process. The sulfur/nitrogen co-doped carbon fiber (S/N-CF) is prepared by the thermal treatment of thiourea-adsorbed carbon fiber. The doping degree of the carbon fiber is improved by reasonable strategy. S/N-ACF shows a higher amount of S/N doping (4.56 at% N and 3.16 at% S) than S/N-CF (1.25 at% N and 0.61 at% S). S/N-ACF with high S/N doping level involves highly active sites to improve the capacitive performance, and high delocalization electron to improve the conductivity and rate capability when compared with the normal S/N co-doped carbon fiber (S/N-CF). Accordingly, the specific capacitance increases from 1196 mF cm-2 for S/N-CF to 2704 mF cm-2 for S/N-ACF at 1 mA cm-2. The all-solid-state flexible S/N-ACF supercapacitor achieves 184.7 µW h cm-2 at 350 µW cm-2. The results suggest that S/N-ACF has potential application as a CF-based supercapacitor electrode material.
RESUMEN
A two-step hydrothermal route was employed to fabricate a ZnMoO4/CoO nanohybrid supported on Ni foam. The ZnMoO4/CoO nanohybrid shows a three-dimensional criss-crossed structure. The specific surface area is enhanced from 45 m2 g-1 of ZnMoO4 to 67 m2 g-1 of the ZnMoO4/CoO nanohybrid. Furthermore, the existence of electroactive CoO is in favor of reducing the charge transport resistance. The ZnMoO4/CoO nanohybrid electrode possesses a high capacitance of 4.47 F cm-2 at 2 mA cm-2, which is much higher than those of ZnMoO4 (1.07 F cm-2) and CoO (2.47 F cm-2). The ZnMoO4/CoO nanohybrid electrode also exhibits an ultrahigh cycling stability with 100.5% capacitance retention after 5000 cycles at 20 mA cm-2. In addition, an asymmetric all-solid-state supercapacitor was assembled using the ZnMoO4/CoO nanohybrid as the positive electrode and exfoliated graphite carbon paper as the negative electrode. The asymmetric supercapacitor exhibits a superior energy density of 58.6 W h kg-1 at a power density of 800 W kg-1 and a considerable cycling stability with 81.8% capacitance retention after 5000 cycles at 5 A g-1. The ZnMoO4/CoO nanohybrid demonstrates its tremendous advantages and possibilities as a positive electrode material in energy storage applications. Moreover, for a better understanding of the electrochemical behavior, a combined study of experimental measurements and density functional theory calculations is also applied to illustrate the high-performance of the ZnMoO4/CoO nanohybrid.
