Hydrothermal Synthesis Research Articles

High-efficiency phosphorus recovery from hypophosphite and phosphite-containing wastewater via a new electrodialysis enrichment and hydrothermal oxidation coupling process

Hypophosphite is an ideal reducing agent used in industries such as electroplating. However, the presence of high concentrations of hypophosphite and phosphite in industrial wastewater necessitates the consumption of large amounts of strong oxidants to oxidize hypophosphite to phosphate for subsequent removal by precipitation. This study introduces an innovative application of green hydrothermal process for the oxidation treatment of inorganic materials, combined with the ion enrichment advantages of electrodialysis. This novel coupling process achieves efficient enrichment and rapid oxidation of high-concentration hypophosphite and phosphite with minimal chemical consumption and more economical operating costs, yielding high-quality phosphate resources. Under electrodialysis conditions with a particle electrode dosage of 3 %, a voltage of 20 V, and a residence time of 10 h, the total phosphorus in the middle chamber was reduced from 2801.17 mg/L to 119.05 mg/L, achieving an anodic enrichment rate of 95.75 %. Under hydrothermal conditions of 400 °C for 15 min, with an H2O2 doping ratio of 7 % and a Ca(OH)2 doping ratio of 35 g/L, the peak oxidation rates of H2PO2− and HPO32− reached 99.38 %, and 99.39 % of phosphorus was transferred from the liquid phase to the solid phase in recyclable forms such as Ca5(PO4)3OH, Ca3(PO4)2, and FePO4. H2O2 enhances the hydrothermal oxidation process by increasing the concentration of free radicals. Ca(OH)2 acted as a catalyst to enhance •OH generation during the hydrothermal reaction, provided Ca2+ required for phosphorus recycling, and increased the pH to obtain crystalline products with a high Ca/P molar ratio. Compared to conventional advanced oxidation processes, the electrodialysis and hydrothermal coupling process offers a clean alternative for treating high-concentration hypophosphite and phosphite in plating wastewaters, achieving a cost saving of 22.99 %.

Poly-m-aminophenol/CoFe2O4 (p-n) heterojunction: Sustainable decontamination of BPA, ciprofloxacin pollutants from water and its study of antimicrobial performance

The remarkable ability of magnetic p-n heterojunction catalyst constructed with p-type poly-m-aminophenol (PmAP)/n-type Cobalt ferrite (CoFe2O4) catalyst to degrade BPA, ciprofloxacin drug (CIF) and its antibacterial activity in killing the microbes was explored on Gram-positive (S. aureus) and Gram-negative (E. coli). The p-n heterojunction photocatalyst was synthesized easily via hydrothermal reaction followed by chemical oxidative polymerization process. PXRD, FTIR, SEM, HRTEM, XPS, EDX, PL/TRPL, BET surface area, VSM and Uv-DRS techniques were used to confirm the synthesized catalyst's physicochemical characteristics and structural details. At ambient conditions, the synthesized catalyst showed rapid mineralisation of the organic pollutants by nearly 100 % at a concentration of 50 ppm in just one hour, with a catalyst loading of 0.1 g. The mineralisation pathways of the organics were illustrated through the GC–MS and TOC analysis. Furthermore, the disinfection capacity of the heterojunction had showed 5 fold quicker than the individual catalysts. This p-n heterojunction catalyst show excellent activity and quick magnetic separable quality which make it a catalyst for sustainable water purification process in future.

Directed Hydrothermal Synthesis of Aluminosilicates of Various Structural Types and Prospects for Their Use in Medicine

Directed Hydrothermal Synthesis of Aluminosilicates of Various Structural Types and Prospects for Their Use in Medicine

Catalytic Biomass Transformation to Hydrocarbons under Supercritical Conditions over Nickel Supported on Schungite

Liquid fuel production from biomass-derived molecules has received great attention due to the diminished fossil fuel reserves, growing energy demand, and the necessity of CO2 emission reduction. The deoxygenation of oils and fatty acids is a promising process to obtain “green” diesel. Herein, we report the results of the study of the deoxygenation of stearic acid to alkanes as a model reaction. Series of Ni-supported on schungite were obtained by precipitation in subcritical water (hydrothermal deposition) and for comparison via wetness impregnation followed, in both cases, by calcination at 500 °C and a reduction in H2 at 300 °C. The catalyst obtained via hydrothermal synthesis showed a three-fold higher specific surface area with a four-fold higher active phase dispersion compared to the catalysts synthesized via conventional impregnation. The catalysts were tested in stearic acid deoxygenation in supercritical n-hexane as the solvent. Under optimized process conditions (temperature of 280 °C, hydrogen partial pressure of 1.5 MPa, and 13.2 mol of stearic acid per mol of Ni), a close to 100% yield of C10–C18 alkanes, containing over 70 wt.% of targeted n-heptadecane, was obtained after 60 min of reaction.

Punica grantum peel extract decorated Al-MOF scaffold as Solid-State Sensor/Concentrator for the Sensing/Reduction of Cr(VI) and its extended utility as a corrosion inhibitor in Al-Air batteries

The growing presence of hexavalent chromium in environmental and industrial settings highlights the importance of developing an eco-benign platform for real-time in-situ sensing/screening and decontamination. This research presents a facile and portable solid-state optical sensor using waste Punica Granatum, i.e., pomegranate peel extract (PPE) adorn onto Aluminium-based Metal-Organic Frameworks (Al-MOFs) for the sensing of carcinogenic Cr(VI) and its decontamination to benign Cr(III). The sensor fabrication entails a hydrothermal synthesis to form Al-MOF scaffolds decorated with PPE through direct immobilization. Al-MOF exhibits a large surface area with well-defined pore channels that facilitate PPE’s voluminous/uniform anchoring in restricted orientations to serve as an ion-selective probe for specifically targeting ultra-trace Cr(VI). The surface/structural morphology and porosity of the Al-MOF-PPE material are characterized using scanning/transmission electron microscopy and BET/BJH analysis. The reduction of Cr(VI) by the Al-MOF-PPE is validated by electron spectroscopy for chemical analysis, corroborated by a conspicuous color transition from light yellow to dark brown. The efficient reduction of Cr(VI) by Al-MOF-PPE is achieved at pH 2–3, in the linear response range of 0.3–300 ppb and a detection limit of 0.23 ppb for Cr(VI). The sensory system prefers minimal PPE probe content (4 mg) and sensor dosage (5 mg) for ion-sensing and decontamination studies, highlighting its remarkable operational efficacy. Post Cr(VI) reduction, electrochemical studies confirm the utility of Al-MOF-PPE-Cr(III) as a corrosion inhibitor for metal surfaces. Tafel plots demonstrate that Al-MOF-PPE-Cr(III) exhibits cathodic and anodic inhibition characteristics, ensuring excellent surface protection for aluminum electrodes upto 220 min in Al-air batteries. The proposed Al-MOF-PPE offers dual functionality as a naked-eye platform for Cr(VI) decontamination, and the Al-MOF-PPE-Cr(III) material is an excellent corrosion inhibitor for energy storage devices.

A broad-spectrum oxidation capability Ru-CeO2 catalyst for efficient synergistic selective oxidation of benzyl alcohol

Selective oxidation of alcohols to aldehydes by molecular oxygen is one of the most important transformations in multiphase catalysis. In this paper, a catalyst with selective oxidation ability was designed and synthesized for the selective catalytic oxidation of benzyl alcohol. N-doped carbon materials were prepared by high-temperature calcination using hydrothermal reaction products of citric acid and melamine as a carbon source, and a bimetallic catalyst supported by Ru-CeO2 was constructed using the mixture as the carrier for the selective oxidation of benzyl alcohol to benzaldehyde. The results showed that the introduction of CeO2 could effectively improve the oxidizing ability and catalytic activity of the catalyst. The Ru-Ce0.05/NC170–600 catalyst was able to convert 85.5 % benzyl alcohol into benzaldehyde at 140 °C, 6 h, and 2 MPa, and the selectivity for benzaldehyde was 100 %. It was demonstrated by DFT that it was theoretically feasible to generate benzaldehyde by extracting hydrogen atoms from benzyl alcohol molecules. Further, the selective oxidation experiments on other alcohols showed that the catalyst has high activity for the oxidation of various alcohols to generate the corresponding carbonyl products, and it is a catalyst with broad-spectrum selective oxidation ability. In this study, a green synthesis route of benzaldehyde was proposed to solve the problems in the traditional process. Meanwhile, it provides a new idea for the synthesis of carbonyl products by selective oxidation of alcohols.

A Layered Titanate Nanowire Helps Pt/TiO2 Photocatalyst for Solar Hydrogen Evolution from Water with High Quantum Efficiency

Abstract Research into TiO2 photocatalysts for solar H2 evolution from water is still growing for environmentally benign and economically valid H2 production. Herein, in contrast to many researches on the modification of TiO2 toward higher photocatalytic activities, we develop a photocatalytically inactive TiO2-based nanostructure and use it, like graphene, as a booster of a benchmark TiO2. A layered potassium titanate with two-dimensional plate-like particle morphology was converted to the corresponding one-dimensional nanowire form via a hydrothermal reaction, after which the layered potassium titanate nanowire was acid-treated to obtain a layered titanate nanowire. This nanowire was completely inactive toward H2 evolution from water containing methanol under solar simulator irradiation. However, when Pt nanoparticle-loaded P25 TiO2 (Pt/P25) was mixed with a considerably smaller amount of the layered titanate nanowire in water, a durable composite was obtained and the composite showed a good photocatalytic activity three times higher than Pt/P25. The apparent quantum efficiency of the reaction at wavelength of 350 nm was 56%, which was higher than or comparable to those of the state-of-the-art TiO2-based photocatalysts. The possible reason for the enhanced photocatalytic activity of the Pt/P25 and layered titanate nanowire composite involved the transfer of photogenerated holes from Pt/P25 to the nanowire to suppress charge recombination and/or disaggregation (improved dispersion) of Pt/P25 particles on the nanowire.

Kinetic Study and Catalytic Activity of Cr3+ Catalyst Supported on Calcium Silicate Hydrates for VOC Oxidation.

Volatile organic compounds (VOCs) are pollutants that pose significant health and environmental risks, necessitating effective mitigation strategies. Catalytic oxidation emerges as a viable method for converting VOCs into non-toxic end products. This study focuses on synthesizing a catalyst based on calcium silicate hydrates with chromium ions in the CaO-SiO2-Cr(NO3)3-H2O system under hydrothermal conditions and evaluating its thermal stability and catalytic performance. A catalyst with varying concentrations of chromium ions (10, 25, 50, 100 mg/g Cr3+) was synthesized in unstirred suspensions under saturated steam pressure at a temperature of 220 °C. Isothermal curing durations were 8 h, 16 h, and 48 h. Results of X-ray diffraction and atomic absorption spectroscopy showed that hydrothermal synthesis is effective for incorporating up to 100 mg/g Cr3+ into calcium silicate hydrates. The catalyst with Cr3+ ions (50 mg/g) remained stable up to 550 °C, beyond which chromatite was formed. Catalytic oxidation experiments with propanol and propyl acetate revealed that the Cr3+ catalyst supported on calcium silicate hydrates enhances oxygen exchange during the heterogeneous oxidation process. Kinetic calculations indicated that the synthesized catalyst is active, with an activation energy lower than 65 kJ/mol. This study highlights the potential of Cr3+-intercalated calcium silicate hydrates as efficient catalysts for VOC oxidation.

Zinc cations incorporated in Silicalite-1 zeolite assist in anchoring atomically dispersed platinum catalyst for boosted and robust propane dehydrogenation

The utilization of Pt-based catalysts in the catalytic conversion of propane to propylene (PDH) remains pivotal in industrial processes. However, the scarcity of Pt and its high cost necessitates innovative strategies to enhance Pt dispersion and catalytic performance. In this study, we present an approach involving the in-situ incorporation of Zn cations into Silicalite-1 (S-1) zeolite through one-pot hydrothermal synthesis, which facilitates the anchoring of atomically dispersed Pt atoms. The synthesized 0.5Pt/Zn@S-1 catalyst exhibits the dehydrogenation performance of 25 % propane for approximately 34.2 % propane conversion and 95.1 % propylene selectivity (propylene turnover rate of 14.2 s−1), coupled with robust stability of up to 60 h without distinct deactivation under a WHSV of 49.1 h−1. Comprehensive characterizations reveal the formation of atomically dispersed Pt-Zn catalytic sites. The Pt atoms are incorporated with the Zn cations and dense silanol nests. This unique configuration facilitates a synergistic effect between Pt and Zn for dehydrogenation.

Bimetal-carbon engineering for polypropylene conversion into hydrocarbons and ketones in a Fenton-like system

Fenton-like reaction with targeted reactive species was tested for up-cycling of waste plastics to value-added chemicals and we demonstrated a bimetal-carbon-activated peroxymonosulfate (PMS) Fenton-like system for effectively converting polypropylene into hydrocarbons and ketones. In a hydrothermal reaction process at 160 °C for 14 h, directional polypropylene conversion was achieved at a selectivity of 80 wt% hydrocarbons and ketones in the products. The distribution of Cu-Mg bimetallic sites on a carbon substrate exhibited a synergistic effect, and their catalytic activation of PMS induced specific generation of •OH-dominated reactive species. The target reactive species controlled the oxidizing capacity of the system. The efficient breaking of C-C/C-H bond in polypropylene and the subsequent further oxidation under mild conditions led to the dominated products of hydrocarbons and ketones. This study provides an attractive approach for upcycling waste plastics, thus promoting circular economy and carbon reduction.

Simple and efficient synthesis of [Ca24Al28O64]4+(4e−) electronic compounds and preliminary exploration of its electron emission as a cathode emitter

[Ca24Al28O64]4+(4e−) electronic compound (C12A7:e−) is a ceramic with extremely low work function, and it exhibits outstanding potential in cathode electron emission. However, the existing preparation methods for this material are cumbersome, time-consuming, and have limited electron density. In this paper, C12A7:e− were prepared using high-pressure hydrothermal reaction and plasma activation sintering. The free O2− in the cages of the sample achieved accelerated diffusion and transition under the high temperature, strong electric field, high-energy pulse current, and plasma activation. Meanwhile, a high concentration of electrons (2 × 1021 cm−3) was rapidly injected into the sample. In addition, the C12A7:e− blocks have fewer defects, such as pores, cracks, and impurities, and their relative density reaches 99.6 %. The electron emission density and effective work function of the C12A7:e− are 1.49 A/cm2 and 2.25 eV, respectively, at 1100 °C. This article provides a reference for preparing C12A7:e− and their applications in electronic emission.

MoO3 with the Synergistic Effect of Sulfur Doping and Oxygen Vacancies: The Influence of S Doping on the Structure, Morphology, and Optoelectronic Properties.

Molybdenum trioxide (MoO3) is an attractive semiconductor. Thus, bandgap engineering toward photoelectronic applications is appealing yet not well studied. Here, we report the incorporation of sulfur atoms into MoO3, using sulfur powder as a source of sulfur, via a self-developed hydrothermal synthesis approach. The formation of Mo-S bonds in the MoO3 material with the synergistic effect of sulfur doping and oxygen vacancies (designated as S-MoO3-x) is confirmed using Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). The bandgap is tuned from 2.68 eV to 2.57 eV upon sulfur doping, as confirmed by UV-VIS DRS spectra. Some MoS2 phase is identified with sulfur doping by referring to the photoluminescence (PL) spectra and electrochemical impedance spectroscopy (EIS), allowing significantly improved charge carrier separation and electron transfer efficiency. Therefore, the as-prepared S-MoO3-x delivers a sensitive photocurrent response and splendid cycling stability. This study on the synergistic effect of sulfur doping and oxygen vacancies provides key insights into the impact of doping strategies on MoO3 performance, paving new pathways for its optimization and development in relevant fields.

Hydrothermal synthesis of carbon dots incorporated in magnetite iron oxide nanoparticles for potential targeted brain cancer therapy: In-Vitro study

Surface modification of magnetite (Fe3O4) nanoparticles (NPs) using carbon dots (CDs) is a promising approach in biomedical applications due to excellent biocompatibility. Herein, the CDs were incorporated in the Fe3O4 NPs to observe the performance of CDs-Fe3O4 NPs for targeted brain cancer therapy. Scanning electron microscopy (SEM) images revealed the morphology of Fe3O4 NPs is rough and agglomerated. X-ray diffraction (XRD) diffraction pattern exhibits that the CDs are successfully incorporated in Fe3O4 NPs. Furthermore, magnetic properties evaluated using vibrating sample magnetometer (VSM) exhibited significant magnetization (51.362 emu/g) attributed to the greater occupancy of Fe+2 ions in the crystal lattice. XRD pattern confirmed the formation of NPs. Furthermore, functional groups of the NPs were validated through Fourier-transform infrared spectroscopy (FT-IR). The measurement of zeta potential affirmed the stability of the as-prepared Fe3O4 NPs, CDs, and CDs-Fe3O4 NPs, indicating a value of −7.64 mV, −0.5754 mV and −3.881 mV, respectively. Fe3O4 NPs exhibited a surface area of 58.6 m2/g as determined by Brunauer-Emmett-Teller (BET) analysis. The anticancer activity of the synthesized CDs-Fe3O4 NPs demonstrated inhibition against MG-U87 cells. Therefore, the synthesized CDs-Fe3O4 NPs hold potential for application in brain cancer therapy. In addition, CDs-Fe3O4 NPs exhibited exceptional biocompatibility and low cytotoxicity against osteoblast cells, establishing them as a safe biomaterial for biomedical applications.

A Multi‐Active Site Subnano Heterostructures Catalyst Grown In situ POM and Fe0.2Ni0.8Co2O4 onto Nickel Foam Toward Efficient Electrocatalytic Overall Water Splitting

AbstractDesigning efficient, durable, and cheap bifunctional electrocatalysts is a challenging goal in water splitting. Herein, trivanadium‐substituted Keggin‐type polyoxometalate H6PV3Mo9O40 (POM) and Fe0.2Ni0.8Co2O4 (FNCO) are in situ grown onto nickel foam (NF) yielding a self‐supporting nanoflower‐like heterojunction via convenient hydrothermal reaction. The POM‐Fe0.2Ni0.8Co2O4/NF as HER and OER electrocatalyst, displays low overpotential (89 and 259 mV) and high electrode stability at 10 mA cm−2. POM‐FNCO/NF as the cathode and anode requires a lower voltage (1.58 V) to provide 10 mA cm−2 for overall water splitting (OWS), which is better than that of commercial catalysts. The electronic sponge characteristics of POM provide more active sites and fast reaction kinetics for HER and OER. The synergy of POM and FNCO optimizes the electron distribution at the interface and enhances the intrinsic activity of HER/OER. Density Functional Theory (DFT) calculations show that water molecules preferentially bind to Co sites on POM‐FNCO. Additionally, POM has proton‐coupled electron transfer properties and its modified FNCO exhibits thermodynamic advantages. The synergistic effect of these two factors enables the efficient overall water splitting of POM‐FNCO. This study offers a novel pathway for the construction of self‐supporting efficient catalysts by in situ growth of POM nanoclusters and spinel oxide sub‐nanometer heterojunctions on NF.

Assessment of the engineering properties of concrete prepared with aggregates developed from waste basalt mud

The development of high-performance aggregate is a key direction of sustainable concrete. One effective synthetic technology for producing artificial aggregates is hydrothermal synthesis. Using waste basalt mud from the construction of a low-carbon industrial park as a raw material further facilitates the utilization of solid waste resources. Therefore, this paper adopted the hydrothermal synthesis method to produce artificial aggregates developed from basalt mud (AABM). Subsequently, it was used to partially replace mechanical aggregate in the preparation of concrete with strength grad C30. The engineering properties of concrete prepared with AABM (C-AABM), including workability, densities, mechanical properties, and frost resistance, were investigated to assess the feasibility of using AABM as concrete aggregates. The results showed that the fluidity of C-AABM can be significantly improved by using AABM. The hardened C-AABM, prepared with 10 ∼ 30 vol% AABM instead of mechanized aggregate, exhibited a dry density decrease of less than 5 %, indicating the feasibility of using AABM for ordinary concrete. However, excessive AABM negatively affected the mechanical properties of the concrete. When the AABM substitution was no more than 15 vol%, the impact of AABM on the compressive strength and modulus of elasticity of C-AABM was less than 15 %. Nevertheless, the performance of the concrete deteriorated dramatically with the addition of AABM under freezing conditions. As described, the primary engineering advantage of preparing C30 concrete with AABM is to improve the workability of the fresh matrix without significantly reducing the mechanical properties of the hardened concrete. It proves the viability of AABM as an alternative aggregate for ordinary concrete production.

Synthesis, Structures, and Magnetic Investigations of Nickel Phosphates: Ni2(PO4)(OH), Ni7(PO4)3(HPO4)(OH)3, and NaNiPO4 Including Potential Haldane Behavior.

Three novel nickel-phosphate structures are reported, Ni2(PO4)(OH) (I), Ni7(PO4)3(HPO4)(OH)3 (II), and NaNiPO4 (III). Each new system was prepared via a high-temperature hydrothermal synthesis at 600-650 °C. All three compounds are built of quasi-one-dimensional (quasi-1-D) Ni2+ containing chains with varying phosphate bridging modes and were characterized by single crystal X-ray diffraction and magnetic susceptibility. All three compounds display very different magnetic behavior. Anisotropic magnetic data is reported for Ni2(PO4)(OH) (I) exhibiting slow antiferromagnetic ordering in the high-temperature regime with substructures that begin to form below 32 K at different field strengths. These characteristics affirm I as being one of the few Haldane-like material candidates. The Ni7(PO4)3(HPO4)(OH)3 (II) material is a member of the unusual ellenbergerite structural family and displays complex inter- and intrachain magnetic interactions while NaNiPO4 (III) shows antiferromagnetic ordering near 18 K. This magnetic behavior is correlated with their structures.

Study on the synergistic hydrogen production performance and mechanism of NiO/WO3-biochar composite material in the photocatalytic 5-hydroxymethylfurfural conversion to 2,5-furandicarboxylic acid

In this work, a simple hydrothermal synthesis method is used to prepare photocatalytic NiO/WO3-biochar composite material, which is applied to catalyze the one-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with synergistic hydrogen production. The optoelectronic properties of NiO/WO3-biochar composite material are characterized. The results indicate that the p-n heterojunction-coupled biochar structure between NiO and WO3 in the NiO/WO3-biochar composite is an important prerequisite for ensuring the one-step oxidation reaction of 5-hydroxymethylfurfural. The experimental results reveal the possible reaction pathways. Under the optimal ratio of NiO/WO3-biochar composite material, the 5-hydroxymethylfurfural conversion rate reaches 100%, the 2,5-furandicarboxylic acid yield reaches 99.6%, and the Faraday efficiency of hydrogen evolution is 98%. This study provides a new approach for the one-step photocatalytic synthesis of 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural, as well as a novel and efficient catalyst for photocatalytic oxidation technology.

Catalytic hydrothermal carbonization of corn and rice straws with citric acid: Implications for charcoal production and combustion performance

Hydrothermal carbonization represents a promising environmental approach for converting biomass into high-quality biochar fuel. Despite extensive discourse, limited research has focused on fuel properties and combustion performances of biochar as well as reaction mechanisms under catalysts. This study scrutinized properties of biochar from citric acid-catalyzed carbonization. Straw (corn/rice) was hydrothermally carbonized in 5 % citric acid solution with a solid-liquid ratio of 1:10 g/mL at 190–250 °C for 3 h. Results revealed an increase in C and a decrease in O with elevated temperature and citric acid concentration. The calorific values for corn and rice straw biochar ranged from 23.53 MJ/kg to 29.81 MJ/kg and from 23.14 MJ/kg to 26.98 MJ/kg, respectively. This study highlighted diverse impacts of hydrothermal reaction temperature and citric acid concentration on biochar attributes, calorific value, energy density, mass yield, energy yield, and thermal stability. It elucidated the influence of citric acid concentration on biochar burnout temperature and the role of hydrothermal reaction temperature and heating rate in biochar combustion characteristics. Citric acid effectively reduced biochar activation energy in low-temperature areas and prolonged the biochar combustion reaction time, achieving highly favorable comprehensive combustion characteristics at 47.56×10−7. The findings present the potential for biochar production with enhanced performance for integrating and co-firing with conventional fuels.

Phase-controlled synthesis of starch-derived Mo2C–MoC/C heterostructure catalyst for electrocatalytic hydrogen evolution reaction

The electronic structure of molybdenum carbide closely resembles that of Pt, making it a promising candidate material for replacing noble metal catalysts. However, the primary challenge is the controlled and eco-friendly synthesis of molybdenum carbide. Herein, we developed a sustainable and controlled method for synthesizing a heterostructure catalyst for the electrocatalytic hydrogen evolution reaction (HER) using starch as the raw material. Through a hydrothermal redox reaction and subsequent temperature-programmed treatment under an inert atmosphere, the hexagonal Mo2C-cubic MoC heterostructure nanoparticles were dispersed on a carbon matrix. Our investigation into the synthesis process extensively covered the growth of MoO2 nanocrystals and hydrochar during the hydrothermal redox reaction, as well as the phase evolution during the subsequent temperature-programmed treatment. Electrochemical assessments demonstrated the catalyst's remarkable efficiency for the hydrogen evolution reaction across both acidic and alkaline media, achieving a current density of 10 mA/cm2 with an overpotential of 139.4 mV in 1 M KOH solution and 160.7 mV in 0.5 M H2SO4 solution. Combining a series of electrochemical characterizations and applying the distribution of relaxation times (DRT) analysis to operando electrochemical impedance spectroscopy (EIS) data, the superior kinetic performance of the Mo2C–MoC/C was demonstrated, outperforming that of single-phase molybdenum carbide. Furthermore, the catalyst has demonstrated remarkable stability even at high current densities in both acidic and alkaline electrolytes, underscoring its potential as a cathode catalyst in both alkaline water electrolyzers and proton exchange membrane (PEM) electrolyzers.

Efficiency and mechanism of modified carbon nitride for the co-adsorption of copper and tetracycline from water

The escalating contamination of heavy metal ions and antibiotics in the aqueous environment underscores the necessity of developing efficient treatment technologies for their concurrent removal. In this work, a phosphate-modified g-C3N4(PCN) by assembling phytic acid with graphitized carbon nitride was prepared through a hydrothermal reaction. The characterization results reveal that PCN exhibits increased porosity, an enhanced specific surface area, and larger pore volume in comparison to pristine CN. At pH 5.0 and 25 °C, PCN demonstrates remarkable adsorption capacities for Cu (II) (q = 172.3 mg g−1) and tetracycline (TC) (q = 63.1 mg g−1) in a single system, respectively, which correspondingly surpasses those of CN by 7 and 8 times. In systems where Cu (II) and TC coexist, Cu (II) enhances the TC removal rate by acting as a bridge. As Cu(II) concentration increases, TC adsorption efficiency significantly improves. Although common ions in solution influence PCN adsorption, it maintains high efficiency for TC and Cu(II) across various water matrices and in the presence of natural organic matter. Detailed characterization and computational chemical analysis reveal that the enhanced adsorption capacity of PCN is due to increased porosity and the presence of additional functional groups. Surface complexation and adsorption bridging are identified as the key mechanisms for effective Cu(II) and TC adsorption. Additionally, recycling experiments validate its reusability, thereby offering a novel avenue for the removal and recovery of TC and Cu(II) from wastewater.