Molecular design of heterogeneous electrocatalysts using tannic acid-derived metal-phenolic networks

Sustainable upcycling of copper from waste printed circuit boards with the assistance of tannic acid and Fe3+ to a magnetic heterogeneous catalyst

The recovery and upcycling of metals from electronic waste into functional materials for wastewater treatment is a win-win strategy for simultaneously realizing electronic waste recycling and wastewater purification. This study focused on converting Cu from waste printed boards (PCBs), a common Cu-rich electronic waste, into CuFe2O4 supported on a mesoporous carbon framework (PCFT) with the assistance of Fe3+ and tannic acid (TA). Compared to the PCF prepared without TA, the resulting PCFT exhibited excellent magnetic properties, high crystallinity, lower interfacial transfer resistance, more abundant oxygen vacancies (OV), and lower metal leaching. Moreover, PCFT can serve as a superior heterogeneous catalyst to activate peroxymonosulfate to remove reactive brilliant blue KN-R from wastewater, and its catalytic activity was markedly higher than that of CFT synthesized with Cu(NO3)2·3H2O, which may be due to its higher specific surface area and more abundant OV. The combined results of scavenging experiments, electron paramagnetic resonance analysis, and electrochemical measurements implied that both radical and nonradical processes promoted the elimination of KN-R; however, •OH and SO4•- were not the major contributors. Furthermore, the PCFT exhibited high adaptability to pH and water matrices, confirming its practical application potential. These findings provide a novel strategy for the upcycling of metals from electronic waste.

MPNTEXT: An Interactive Platform for Automatically Extracting Metal-Polyphenol Networks and Their Applications from Scientific Literature

In recent years, metal-polyphenol networks (MPNs) have gained significant attention due to their unique properties and broad applications across various fields. However, the burgeoning volume of MPN literature necessitates the automation of chemical information extraction from the extensive corpus of unstructured data, including scientific publications. To address this challenge, we proposed a platform named MPNTEXT, which utilized natural language processing techniques and machine learning algorithms to efficiently identify and extract pertinent information, thereby assisting users in comprehending complex MPNs and their textual descriptions of applications. Users can enter keywords, such as "Fe", "drug delivery", or "tannic acid", to retrieve relevant information, which is then presented in a structured format. This study aims to provide a user-friendly tool for collecting and retrieving MPN data and promotes data-driven material design. The platform offers researchers a more convenient and efficient way to design versatile MPNs and explore their applications.

Ultrathin layer TAFC on BiVO4 with ligand-to-metal charge transfer enhances built-in electric field for boosting photoelectrochemical water oxidation

To reveal the mechanism of charge transfer between interfaces of BiVO4-based heterogeneous materials in photoelectrochemical water splitting system, the cocatalyst was grown in situ using tannic acid (TA) as a ligand and Fe and Co ions as metal centers (TAFC), and then uniformly and ultra-thinly coated on BiVO4 to form photoanodes. The results show that the BiVO4/TAFC achieves a superior photocurrent density (4.97 mA cm-2 at 1.23 VRHE). The charge separation and charge injection efficiencies were also significantly higher, 82.0 % and 78.9 %, respectively. From XPS, UPS, KPFM, and density functional theory calculations, Ligand-to-metal charge transfer (LMCT) acts as an electron transport highway in TAFC ultrathin layer to promote the concentration of electrons towards metal center, leading to an increase in the work function, which enhances the built-in electric field and further improves the charge transport. This study demonstrated that the LMCT pathway on TA-metal complexes enhances the built-in electric field in BiVO4/TAFC to promote charge transport and thus enhance water oxidation, providing a new understanding of the performance improvement mechanism for the surface-modified composite photoanodes.

The physico-chemical and antimicrobial properties of nano ZnO functionalised tannic acid

Tannic acid (TA) has been reported as an efficient plant-based compound with inhibitory activity against viruses and bacteria. The combination of TA with Zinc Oxide (ZnO) nanostructures with ZnO is one of the most widely used nanoparticles for antimicrobial properties, have not yet fully elucidate especially their mechanisms of overall physicochemical and antimicrobial actions. Hence, to observe the influence of TA adsorption on ZnO, the investigations on the TA concentration and the effect of pH towards the physicochemical, optical and antimicrobial properties are demonstrated. The pure ZnO are synthesised via the chemical reduction method and the ZnO-TA nanostructures are further prepared using the dropwise methods to form variations of pH samples, which causes the formation of different mean particle size distribution, d m . The findings reveal that the performance of physicochemical and optical properties of pure ZnO and ZnO-TA are different due to the wrapped layers of TA which change the charged surface of all the particles. The protonation reactions yield strong pH dependence (pH 3 and 5), with uptake performance becoming more dominant at higher TA concentration loading (pH 3). The detailed optical energy bandgap and Urbach energy that concluded the nanoparticle growth and disorder condition of produced particles are presented. For antimicrobial efficiency, ZnO-TA shows improved effectiveness in growth inhibitions of S. aureus 99.69% compared to pure ZnO nanostructure (99.39%). This work reveals that the TA concentration increases the overall performance, and the discussion gives added support to their potential performance related to the field of ZnO compound.

Metal-phenolic networks derived CN-FeC hollow nanozyme with robust peroxidase-like activity for total antioxidant capacity detection

A tannate-iron network-derived peroxidase-like catalyst loaded with Fe ions on carbon nitride (C3N4) was reported for detection of total antioxidant capacity (TAC) in food in this study. Metal-phenolic networks (MPNs) was employed to form a low coordination compound on C3N4, and calcined catalyst formed hollow structure with abundant and uniform Fe sites and surface folds. CN-FeC exhibited significant peroxidase-like activity and high substrate affinity. The homogeneous distribution of amorphous Fe elements on the C3N4 substrate provides more active sites, resulting in provided excellent catalytic activity to activate H2O2 to ·OH, 1O2 and O2·-. The established CN-FeC/TMB/H2O2 colorimetric system can detect AA in the concentration range of 5-40 μM, with the detection limits of 1.40 μM, respectively. It has good accuracy for the detection of vitamin C tablets, beverages. Taken together, this work shows that metal-phenolic networks can be an effective way to achieve efficient utilization of metal atoms and provides a promising idea for metal-phenolic networks in nanoparticle enzyme performance enhancement.

Electrochemical Evolution of Ru-Based Polyoxometalates into Si,W-Codoped RuOx for Acidic Overall Water Splitting

Despite intensive studies over decades, the development of electrocatalysts for acidic water splitting still relies on platinum group metals, especially Pt and Ir, which are scarce, expensive, and poorly sustainable. Because such problems can be alleviated, Ru-based bifunctional catalysts such as rutile RuO2 have recently emerged. However, RuO2 has a relatively low activity for hydrogen evolution reactions (HER) and low stability for oxygen evolution reactions (OER) under acidic conditions. In this study, the synthesis of a RuOx -based bifunctional catalyst (RuSiW) for acidic water splitting via the electrochemical evolution from Ru-based polyoxometalates at cathodic potentials is reported. RuSiW consists of the nanocrystalline RuO2 core and Si,W-codoped RuOx shell. RuSiW exhibits outstanding HER and OER activity comparable to Pt/C and RuO2 , respectively, with high stability. Computational analysis suggests that the codoping of RuOx with W and Si synergistically improves the HER activity of otherwise poor RuO2 by shifting the d-band center and optimizing atomic configurations beneficial for proper hydrogen adsorption. This study provides insights into the design and synthesis of unprecedented bifunctional electrocatalysts using catalytically inactive and less explored elements, such as Si and W.

Photocatalytic H2O2 production from water and air using porous organic polymers

Producing hydrogen peroxide (H2O2) from H2O and O2 under visible light irradiation is a promising solar-to-chemical energy conversion technology. Hydrogen peroxide has versatile applications as a green oxidant and liquid energy carrier but has been produced through energy-intensive and complex anthraquinone processes. Herein, we report the rational design of efficient and stable porous organic polymer (POP) containing redox centers, anthraquinone photocatalyst (ANQ-POP) for solar H2O2 production. ANQ-POP is readily synthesized with stable dioxin-linkages via efficient one-pot, transition-metal-free nucleophilic aromatic substitution reactions between 1,2,3,4,5,6,7,8-octafluoro-9,10-anthraquinone (OFANQ) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP). Exhibiting a fibrillar morphology, ANQ-POP boasts a high surface area of 380 m2∙g-1 and demonstrates thermal stability. With 10 % ethanol, ANQ-POP yields an H2O2 production rate of 320 μmol g-1 under visible light irradiation. Moreover, ANQ-POP alone can efficiently produce H2O2 without any photosensitizers and cocatalysts. Density functional theory calculations reveal that the quinone groups of the anthraquinone moieties can serve as redox centers for H2O2 production under light irradiation. Furthermore, unlike most conventional photocatalysts, it can produce H2O2 using only water and air by catalyzing both oxygen reduction and evolution reactions under light irradiation. Our findings provide an efficient, eco-friendly pathway for photocatalytic production of H2O2 under mild reaction conditions using a dioxin-derived POP-based photocatalyst.

Single-site bipyridine cobalt complexes covalently embedded into graphitic carbon nitride with excellent photocatalytic activity and selectivity towards CO2 reduction

A combination of a semiconductor-based photosensitizer with molecular catalysts via covalent bonds is an effective way to utilize solar energy to reduce CO₂ into value-added chemicals with high efficiency and selectivity. In this study, 2,2'-bpy-5,5'-dialdehyde functioned as organic ligands and were embedded into the skeleton of g-CN through imine bonds via thermal copolymerization. The introduction of 2,2'-bpy can not only chelate with earth-abundant Co as single-site catalytic centers but also can optimize the properties of original g-CN such as the enlarged specific surface area and extended visible light absorption range. The CO evolution rate of g-CN-bpy-Co can reach up to 106.3 μmol g^-1 h^-1 with a selectivity of 97% over proton reduction, which was 82-fold than that of g-CN-Co. The different coordination environments and valence states of cobalt were also studied simultaneously and the results showed that Co(II) exhibited superior catalytic activity towards Co(III). Control experiments demonstrated that the covalent linkage between g-CN and Co-2,2'-bpy plays a vital role in photocatalytic activity and selectivity. Besides, the CO generation rate demonstrated linear growth upon visible light irradiation up to 72 h and preferable recyclability. This research provides a new facile way to fabricate low-priced photocatalysts with high activity and selectivity and bridge homogeneous and heterogeneous catalysis.