3 research outputs found
Sulfur vacancy-rich tungsten disulfide and metal-organic framework derived Co3O4 heterostructure for sulfur ion degradation-assisted efficient hydrogen production
No full textThe rapid advancement of the hydrogen economy hinges on developing efficient systems that combine the sulfion oxidation reaction (SOR) and hydrogen evolution reaction (HER) to achieve cost-effective hydrogen production. Herein, a metal–organic framework derived Co3O4-integrated WS2 (CW) heterostructure with sulfur-rich vacancies was synthesized via a hydrothermal process. This ultrathin nanosheet structure afforded efficient electrocatalytic performance towards oxygen evolution reaction (OER), HER, and SOR by providing abundant active sites and optimal electronic configurations. The optimal CW heterostructure exhibited excellent OER and HER performance with lower overpotentials of 270 and 153 mV, respectively. The higher turnover frequency of the CW-2 electrocatalysts is 0.226 s−1 at the potential of 1.65 V. In situ/operando X-ray absorption spectroscopy (XAS) provided detailed insights into the dynamics at the catalyst surface and structural evolution under electrochemical conditions. In situ/operando XAS demonstrated a decrease in the coordination number of W–S when the applied potential was increased to 1.55 V due to the formation of sulfur vacancies. Sulfur and metal vacancies were plausibly co-existent, as demonstrated by the variation in the coordination number for the W–S first shell with the applied voltage, and the similar trend for the W–W second shell. Because of these advantages, the CW heterostructure exhibited better electrocatalytic activity for the OER, HER, and SOR. The assembled system with the CW-2 heterostructure established a remarkably low cell voltage of 0.41 V (@ 10 mA cm−2) for driving the cathodic HER and anodic SOR, with high faradaic efficiency (86.27%), and exceptional durability over 80 h. The findings of this study should contribute significantly to energy-efficient hydrogen production and sustainable sulfion recycling through the development of robust and highly effective catalysts.補正完畢GB
Interfacial oxygen vacancy modulated ZIF-8-derived ZnO/CuS for the photocatalytic degradation of antibiotic and organic pollutants: DFT calculation and degradation pathways
No full textFabricating oxygen vacancies (Vo) is an effective approach to enhance photocatalytic performance, but its effect on the interfacial charge transfer pathway remains unelucidated to date. In this study, we used the simple aqueous solution method to create an oxygen-defected ZIF-8-derived CuS/ZnO (CZ) heterostructure, and various characterization techniques were used to investigate the prepared catalysts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to determine the surface defects caused by the CuS nanoparticles in the ZnO matrix generated from ZIF-8. The optimized CuS/ZnO (CZ-2) catalyst exhibited efficient photocatalytic performance by effectively increasing the charge separation rate of the photogenerated electrons. The photocatalytic performances of methylene orange (MO) and ciprofloxacin (CIP) using the CZ heterostructure were 99.76 % and 94.59 %, respectively, with the corresponding rate constants of 0.0695 and 0.0312 min−1 at 40 min. The electron spin resonance and scavenger tests have established that •O2− is the primary oxidative radical species involved in photocatalytic activity. In addition, the density functional theory calculations were performed to determine the degradation mechanism of CIP, and the possible pathways of CIP degradation were investigated using liquid chromatography–mass spectroscopy. This study provides new insights into the development of metal–organic frameworks and metal sulfide-based heterostructures for environmental degradation applications.補正完畢NL
Novel heterostructure-based CoFe and cobalt oxysulfide nanocubes for effective bifunctional electrocatalytic water and urea oxidation
No full textThe development of effective oxygen evolution reaction (OER) and urea oxidation reaction (UOR) on heterostructure electrocatalysts with specific interfaces and characteristics provides a distinctive character. In this study, heterostructure nanocubes (NCs) comprising inner cobalt oxysulfide (CoOS) NCs and outer CoFe (CF) layered double hydroxide (LDH) are developed using a hydrothermal methodology. During the sulfidation process, the divalent sulfur ions (S2−) are released from the breakdown of the sulfur source and react with the Co-precursors on the surface leading to the transformation of CoOH nanorods into CoOS nanocubes. Further, X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) analyses reveal that the interactions at the interface of the CF@CoOS NCs significantly altered the electronic structure, thus enhancing the electrocatalytic performance. The optimal catalysts exhibited effective OER and UOR activities, the attained potentials are 1.51 and 1.36 V. This remarkable performance is attributable to the induction of electron transfer from the CoFe LDH to CoOS, which reduces the energy barrier of the intermediates for the OER and UOR. Furthermore, an alkaline water and urea two-cell electrolyzer assembled using CF@CoOS-2 NCs and Pt/C as the anode and cathode requires a cell voltage of 1.63 and 1.56 V along with a durability performance.補正完畢DE
