Facilitated Visible-Light-Driven Peroxymonosulfate Activation by a Co–Fe Layered Double Hydroxide Derived p–n Heterostructure for Sulfadiazine Degradation: Affecting Parameters, Kinetics, and Mechanistic Insights

Abstract

The utilization of multivalence ionic metal species generated through a peroxymonosulfate (PMS)-assisted photocatalytic system is a promising platform for the selective degradation of water contaminants. However, achieving an effective electron transport and enhanced separation efficiency for these metal species is a daunting challenge. Thus, our current study addresses this challenge by using a Co−Fe-based layered-double-hydroxide template to synthesize a Co 3 O 4 /FeCo 2 O 4 p−n heterojunction composite via a simple monosynthetic route. The resultant composite is thoroughly validated through advanced characterization techniques that efficiently activate PMS for sulfadiazine (SDZ) degradation under visible light, achieving a remarkable degradation efficiency of up to 90%. This accomplishment is attributed to factors including intimate interfacial contact, excellent light harvesting, mesoporosity, and oxygen vacancies within the composite. The formation of a distinct p−n heterojunction following the S-scheme charge dynamic significantly enhances photogenerated carrier separation and reduces charge recombination. The research delves into comprehensive investigations including degradation studies, active species trapping experiments, parameter exploration, and in-depth liquid chromatography−mass spectrometry for analysis of the degradation byproducts and pathway. Induced oxygen vacancies, strategically placed active surface sites, and mesoporosity in the Co 3 O 4 /FeCo 2 O 4 composite synergistically boosted the sluggish PMS activation, leading to enhanced SDZ degradation. This study introduces a new perspective by demonstrating the potential of a single-material, mixed-metal oxide-based p−n heterojunction photocatalytic system following the S-scheme charge-transfer route for SDZ degradation. The findings contribute toward emphasizing the importance of tailored composite materials in tackling persistent contaminants.

In Situ Synthesis of Exfoliated Ni(OH)2 Nanosheets and AgNPs-Embedded Functionalized Polyindole-Based Trinary Hybrid Microspheres: A Z-Scheme Photocatalyst for the Sunlight-Driven Degradation of Organic Pollutants with Enhanced Antibacterial Efficacy

“…Furthermore, time-resolved photoluminescence (TRPL) spectra of the synthesized materials are displayed in Figure S8e. The TRPL spectra demonstrate a strong correlation with the separation and recombination rate of photoexcited electron–hole pairs as well as the nonradiative emission rate and fluorescence lifetime of photoexcited electrons . The determined average excited lifetimes (τ avg ) of photoexcitons for PIn/MAA, Ni(OH) 2 microflowers, NH/PIn/MAA, and NH/PIn/MAA/Ag are 0.77, 0.84, 0.87, and 0.95 ns, respectively.…”

“…Usually, the flat band potential ( E fb ) of semiconducting materials can be measured by the MS plot, which is rational to deduce the band edge structure. Upon extrapolating the X -axis, the negative MS slope of Ni(OH) 2 microflowers and the positive MS slope of PIn/MAA ascertain the p-type and n-type electronic nature, respectively, whose flat band potentials are practically located close to the valence band (VB) of Ni(OH) 2 microflowers and conduction band (CB) of PIn/MAA, respectively. , Herein, the approximate E fb values of the pristine Ni(OH) 2 microflowers and PIn/MAA are estimated to be +1.76 and −1.39 V vs Ag/AgCl electrodes, respectively (Figure S7e,f). Using eq , the E fb on the normal hydrogen electrode (NHE) scale is determined …”

Decoration of Carbon Dots on Oxygen-Vacancy-Enriched S-Scheme TiO2 Quantum Dots/TiO2 Oxygen Vacancies Photocatalysts: Impressive Quantum-Dot-Sized Photocatalysts for Remediation of Antibiotics, Bacteria, and Dyes

“…As a result, C-dots provide the required photons to produce electrons and holes in the TiO 2 QDs semiconductor. Photoinduced electrons in the CB of TiO 2 OVs combine with the photoinduced holes in the VB of TiO 2 QDs with the help of C-dots as a mediator, and electrons and holes are retained with higher redox power . The electrons in the CB of TiO 2 QDs and the holes in the VB of TiO 2 OVs produced by producing active species, as determined by the scavenger tests, completely destroy the pharmaceutical and dye pollutants or turn them into harmless substances, and they are also utilized in the disinfection of microbial pollutants.…”

Ultrafast Hole Preservation with Undercoordinated Tungsten for Efficient Solar-to-Chemical Conversion

“…In summary, the 1:3.5 MIL (W) metal organic framework derivative is successfully synthesized for efficienct photocatalysis. − High Ov of 28.64% in [WO 6 ] 6– octahedron is achieved through careful adjustment of feed ratio and dechlorination temperature. MIL (W) exhibits exceptional photocatalytic performance, achieving a H 2 O 2 production rate up to 330,000 μmol g –1 h –1 L –1 .…”