The oxygen evolution reaction (OER), serving as the anodic bottleneck in electrochemical water splitting for hydrogen production, severely limits the overall energy conversion efficiency due to its sluggish kinetics. Developing efficient and stable electrocatalysts based on earth-abundant elements is a critical challenge for advancing clean energy technologies. In recent years, silicate materials have demonstrated significant potential in alkaline OER catalysis owing to their unique stable silicon-oxygen tetrahedral framework and flexibly tunable metal-oxygen-silicon electronic coordination environments. This review systematically summarizes recent progress in silicate-based materials, including natural clay mineral supports such as halloysite, for OER electrocatalysis. It focuses on controllable synthesis strategies for silicate materials and provides an in-depth analysis of the regulation mechanisms for their electronic structure and surface properties through defect engineering, anion vacancy construction, and bimetallic/non-metallic heteroatom doping. Particular emphasis is placed on research pathways that utilize natural silicate clay minerals as both supports and silicon sources to construct high-performance composite catalytic materials via innovative structural design and interface engineering. Systematic studies indicate that precisely modulated silicate-based catalysts exhibit excellent electrochemical activity and long-term stability in the alkaline OER process. This review offers perspectives on the future development of efficient and stable silicate-based catalytic systems for renewable energy conversion.

In this work, a sustainable strategy for synthesizing a magnetically recoverable Fe3O4@CaSiO3 (FCSH) adsorbent is proposed, utilizing magnetite tailings as raw materials. An acid leaching and alkali fusion assisted route was used to obtain Fe/Si-containing precursors from magnetite tailings, followed by solvothermal/hydrothermal processing to construct the Fe3O4-based core-shell composite. The optimized FCSH adsorbent exhibits a high specific surface area (240.51 m2/g), sufficient magnetization (40.01 emu/g), and mesoporous structure (10.53 nm), demonstrating excellent adsorption performance and rapid solid-liquid separation capability. Notably, FCSH achieved almost complete removal (approximate to 100%) for Cu2+ with an initial concentration of 250 mg/L, and the maximum adsorption capacity could reach 498.38 mg/g. Adsorption kinetics followed the pseudo-second-order model, while the isotherms were consistent with the Langmuir model, suggesting that the adsorption process was predominantly monolayer chemisorption. Mechanism investigations revealed a synergistic effect involving surface complexation, ion exchange, and hydroxide co-precipitation. Although the removal efficiency decreased by 25.27% after five regeneration cycles, the superior adsorption performance and magnetic recyclability enable FCSH as an ideal candidate for heavy metal remediation. This work not only achieves the reutilization value of industrial solid waste but also provides novel insights into the design and preparation of adsorbent materials.

The low-cost and efficient removal of residual flotation reagents such as xanthates in mineral processing wastewater is a crucial part of building green mines. In this work, Ce-doped black TiO2 was in-situ deposited onto the surface of sepiolite nanofibers using a solvothermal approach. The optimal synthesis conditions were established to be a Ce/Ti molar ratio of 4%, a hydrothermal temperature of 200 °C, a hydrothermal reaction time of 8 h, and a TiO2/sepiolite mass ratio of 0.8: 1. The obtained Ce-doped black TiO2/sepiolite (CBTS) composite photocatalyst demonstrated outstanding degradation performance for xanthates under visible light irradiation. The formation of black TiO2 can be attributed to Ti3+ self-doping, which enables the regulation of the crystal structure and photoelectrochemical properties of pristine TiO2. Moreover, cerium doping can reduce the nanocrystalline particle size of black TiO2 and introduce impurity energy levels to narrow its band gap. After 30 min of dark adsorption followed by 120 min of photocatalytic reaction, the optimal sodium isobutyl xanthate (SIBX) degradation efficiency of 95.5% can be achieved with the initial concentration of 30 mg/L and the CBTS dosage of 0.6 g/L. Moreover, the degradation efficiency of SIBX by the CBTS composite can still remain over 85% after four consecutive cycles. The excellent xanthates removal performance can be ascribed to the synergistic adsorption-photodegradation properties of the CBTS composite.

A novel MoS2 disulfide-loaded NaA zeolite composite (NaA@MoS2) with a core-shell structure was synthesized via a hydrothermal route using fluorite tailings as the silica source. Structural characterizations show that abundant ultrathin MoS2 nanosheets were uniformly anchored on cubic NaA zeolite, forming a dense pore-accessible interface. Under visible light, NaA@MoS2 achieved synergistic adsorption and photocatalytic removal of rhodamine B (RhB). At 100 mg L-1 RhB (50 mL) and a catalyst dosage of 1.0 g L-1, more than 98% RhB was removed within 180 min after 30 min dark adsorption. The composite dosage of 1.0 g L-1 and an initial RhB concentration of 100 mg L-1 at pH approximate to 7 offer a good balance between reaction rate and catalyst utilization. After five cycles, the removal efficiency decreased from similar to 92% to similar to 70%, while post-reaction characterization and leaching tests showed that the crystalline framework and porous architecture were largely retained. RhB+ was preconcentrated at the NaA@MoS2 interface by the porous and negatively charged NaA framework, while visible-light excited MoS2 generated e(-)/h(+) pairs that formed center dot O-2(-)/center dot OH reactive radicals. Optical, electrochemical, and DFT results supported a coupled "adsorption-enrichment-photooxidation" pathway for fast and deep RhB removal. This work provides a promising strategy for tailings valorization and visible-light treatment of organic wastewater.

Ni-based catalysts have been widely used in catalytic reactions by researchers due to their advantages such as abundant resources, high catalytic activity and lower prices than precious metals. However, the problems of easy agglomeration and poor dispersion of Ni-based catalysts have hindered their large-scale application. Therefore, it is necessary to select a suitable preparation method to reduce the agglomeration of the catalyst and improve its dispersion. In this paper, the Ni-NiAl2O4/tourmaline composite material was prepared by using the microwave hydrothermal reduction method. The most favorable conditions for preparing NiAl2O4/tourmaline are as follows: using TEOA as the additive, the microwave hydrothermal temperature is 220 °C, the calcination temperature is 800 °C, and the addition amount of tourmaline is 7.4 wt.%. NiAl2O4 has a good dispersion over the surface of tourmaline support and the optimal NiAl2O4/tourmaline catalyst exhibits a specific surface area of 106.5 m2/g. Metallic nickel was reduced at 650 °C to further obtain Ni-NiAl2O4/tourmaline composites. Finally, the Ni-NiAl2O4/tourmaline composites showed significantly improved catalytic dry reforming of methane (DRM) activity compared to Ni-NiAl2O4 sample under low-temperature conditions (500–600 °C), meaning that the tourmaline carrier could effectively optimize the low-temperature catalytic performance of Ni-NiAl2O4.

In recent years, nickel-based catalysts have attracted more attention in many fields due to their high catalytic activity and low price. However, nickel-based catalysts still have the disadvantages of single carrier and low dispersion of active components, which is not conducive to their large-scale industry application. Herein, a novel Ni-NiAl2O4/tourmaline composite with an intermediate transition layer structure based on tourmaline as a carrier was successfully synthesized via microwave-assisted coprecipitation-reduction method. A series of experiments were conducted to explore the optimal fabrication parameters and the optimal preparation conditions of the Ni-NiAl2O4/tourmaline composite were determined as follows: 0.25 wt% of sodium dodecylbenzene sulfonate, 750 degrees C of calcined temperature, 9.1 wt% of tourmaline additional content, and 650 degrees C of reduced temperature. The introduction of tourmaline can effectively reduce the size of metallic Ni nanoparticles (about 5 nm) and improve the dispersity of NiAl2O4 nanoflakes and Ni nanoparticles. The catalytic performance of NiNiAl2O4 and Ni-NiAl2O4/tourmaline samples for CO2 dry reforming of methane (DRM) was investigated and the probable catalytic mechanism was proposed. This work provides new insights into designing low-cost catalysts for sustainable carbon resource utilization and clean energy production.

Since antibiotic abuse has posed a long-term threat to the ecological environment and human health, it is urgently needed to explore efficient techniques for the rapid removal of remaining antibiotics in wastewater. In this work, combined solvothermal and hydrothermal methods were reported to synthesize novel BiOBr/black-TiO2/ schorl (BTS) ternary composites to achieve the deep elimination of tetracycline (TC) through the adsorptionphotodegradation synergistic effect. A series of characterizations were conducted to investigate the structure, composition, and photoelectric properties of BTS. The results show that compared with pristine BiOBr, blackTiO2 and the counterpart binary composites, BTS exhibited superior adsorption and photodegradation performance towards TC. Among all the samples, BTS-2 demonstrated the optimal TC removal efficiency of 97.7 % with a dosage of 0.6 g/L under visible light irradiation. Based on the electron spin resonance (ESR) experiments, the possible active free radicals are determined during the photodegradation process. A liquid chromatograph mass spectrometer (LC-MS) test was carried out to identify the intermediates of TC degradation and the plausible degradation pathways were proposed. The excellent TC removal performance over the BTS composite can be attributed to the adsorption-photodegradation properties of the sample and the full utilization of the characteristic of each component within the ternary composite.

This study focuses on the prevention and control of polyethylene dust explosion hazards. A novel basic carbonate magnesium-based meso−/microporous core-shell molecular sieve (Hβ@meso-SiO2@BMC) composite explosion suppressant was successfully designed and prepared. First, a composite molecular sieve carrier with a microporous core and mesoporous shell structure, Hβ@meso-SiO2, was prepared using a sol-gel coating process. Then, basic carbonate magnesium (BMC) was loaded onto its surface through an in-situ synthesis method, resulting in a series of composite explosion suppressants with different active component-to-carrier mass ratios. The successful synthesis and microstructural characteristics of the material were confirmed by characterization techniques such as SEM, TEM, BET, XRD, and FTIR. Hartmann deflagration apparatus experimental results showed that the best explosion suppression effect was achieved when the mass ratio of BMC to Hβ@meso-SiO2 was 1:2. When 60 wt% of the composite suppressant was added, the flame propagation of polyethylene dust was almost completely suppressed. Analysis of deflagration products and distributed activation energy model (DAEM) studies indicated that the suppressant works through multiple synergistic inhibition mechanisms: On one hand, the multi-level pore structure provides abundant active sites to adsorb combustion radicals, blocking the propagation of chain reactions. On the other hand, CO2 and H2O released from the thermal decomposition of BMC dilute the oxygen concentration in the combustion zone, and the decomposition product MgO participates in radical capture. Additionally, the high specific surface area of the composite molecular sieve enhances the absorption and dispersion capacity of explosion heat. Thermodynamic analysis further confirmed that after adding this suppressant, the polyethylene pyrolysis activation energy significantly increased (from 155 kJ/mol to 235 kJ/mol), effectively inhibiting the thermal decomposition and deflagration processes. This novel composite suppressant provides a new approach for preventing and controlling dust explosions in polymer materials.

The development of palygorskite rubber filler meets the rubber industry's demand for a low-cost green filler, but the high cost of mineral purification and modifiers limits its industrialization. In an effort to decrease such expenses, this study opted for eco-friendly L-(+)-cysteine as the modifier for organic grafting on the surface of lowgrade palygorskite ore. L-(+)-Cysteine-modified low-grade palygorskite rubber reinforcing filler (CYS@PAL) was successfully prepared through ultrafine ball milling and modification. Under the conditions that the modifier dose is 1 wt% and the filling amount of modified powder is 90 phr, the 100 and 300% constant tensile stress, tensile strength, and elongation at break of reinforced EPDM composite reached 4.07 MPa, 7.66 MPa, 24.78 MPa, and 764.70%, respectively. In addition, after thermo-oxidative aging at 70 degrees C for 48 h, the aging coefficient of the composite rubber reached 0.873. This work provides a low-cost and environmentally friendly method to prepare a high-performance low-grade palygorskite reinforcing filler. [doi:10.5254/rct.24.00059]

The development of efficient and stable oxygen evolution reaction (OER) catalysts is a key challenge in the industrialization of electrolytic water-to-hydrogen technology. Although the traditional noble metal-based catalysts (e.g., IrO2, RuO2) have excellent activities, their scarcity and high cost severely restrict large-scale applications. In this study, natural sepiolite-derived silica (SD-SiO2) was innovatively used as the silica source to construct transition metal silicate hydroxide (TM-Silicate), which exhibits significant advantages with its unique layered-porous composite structure. Obtained structure facilitates the transport of electrons and reaction media. Systematic calculations based on density functional theory (DFT) reveal the decisive role of metal-oxygen bond covalency on the catalytic performance. By calculating the eg occupation and [3d]/[2p] orbital hybridization ratios, it is found that the Co-O bond in Co-Silicate has moderate covalent bonding properties, and its electronic structure achieves an optimal balance between strong adsorption (*OOH/*O species) and fast charge transfer. Experimental data confirm that Co-Silicate requires only 338 mV overpotential to achieve a current density of 10 mA cm-2 in 1.0 M KOH, with a Tafel slope as low as 65 mV dec-1, which is superior to Fe-Silicate (360 mV) and Ni-Silicate (404 mV) materials. Particularly, the novel electrocatalyst shows very little activity decay after constant-current testing, which is attributed to the mechanical stability endowed by the SD-SiO2 backbone. This study provides new structural modulation strategies for the design of noble metal free OER catalysts and demonstrates the great potential of natural minerals for application in the development of energy materials.

The slow reaction rate of the oxygen evolution process (OER) and the high economic burden associated with precious metal catalysts significantly impede the practical adoption of OER-driven technologies. Despite recent advancements, the development of non-precious electrocatalysts with high OER activity and remarkable stability remains a significant scientific challenge. Herein, novel iron-doped cobalt silicate hydroxide (CoFeSi) electrocatalysts assembled with ultrathin nanosheets were successfully prepared using a facile hydrothermal method. Halloysite derivatives (silica nanotubes) were used as the silicon source and sacrificial template to obtain the hierarchical structure CoFeSi. The key influencing factors including hydrothermal temperature, hydrothermal time and iron precursor amounts were investigated in detail. The optimal CoFeSi sample demonstrated the minimal overpotential of 282 mV at 10 mA·cm-2 and the lowest Tafel slope of 57 mV·dec-1, which is obviously superior to the cobalt silicate hydroxide (CoSi) sample. In accordance with the results of 3000 consecutive cyclic voltammetry (CV) cycles and 28 h chronopotentiometry (CP), CoFeSi electrocatalyst showed outstanding long-term stability and durability. A probable enhancement mechanism of OER activity was proposed under the guidance of theoretical calculation. This work not only provides a new strategy to synthesize metal silicate-based electrocatalysts with high OER performance and low-cost, but also reveals that the doping of iron into CoSi can distinctly improve its OER activity.

Bentonite in the environment acts as a natural barrier, buffering and retarding the migration of uranium ions. Its effectiveness is influenced by factors such as pH, ionic strength, and low-molecular-weight organic acids produced by microbial metabolism. However, the role of chiral organic acids remains underexplored. Therefore, our study explored how chiral acids (L/D-malic, L/D-tartaric, L/D-lactic) drive minerals in bentonite, and the link between mineral phase transformations and adsorption/mineralization of heavy metal ions. Research revealed that chiral organic acids variably reduced montmorillonite (MMT) charge density in bentonite, triggering disparate crystal collapse and subsequently altering bentonite's adsorption and mineralization of heavy metal ions. Among them, L-type organic acids resulted in less MMT's negative charge density in bentonite compared to D-type acids (zeta difference, L-type test values minus D-type test values, same for subsequent data: 1.60 mV, 6.20 mV, 4.10 mV, respectively), causing greater crystal collapse (d001 difference:0.10 & Aring;, -0.16 & Aring;, -0.57 & Aring;). This, in turn, further suppressed bentonite surface adsorption (total QL difference:32.04 mg center dot g-1), pore adsorption (total QDR -9.4 mg center dot g1), and interfacial adsorption (total QF -3.27 mg center dot g-1). Conversely, mineralization showed the opposite trend, with increased electron transfer and 1.23-fold more amorphous UO2 in L-bentonite than D-bentonite (Namely, bentonite treated separately with L-type and D-type organic acids). These findings provide new insights and valuable references for in-situ emergency soil treatment and water remediation.

High-performance, low-cost electrocatalysts are essential for freshwater-independent seawater electrolysis. We design a SWCNT-supported (FeCoNiMnCr)3O4 high-entropy spinel oxide by a hydrothermal method and air-firing, where the conductive network enhances charge transfer and active site exposure. The catalyst achieves 282 mV@10 mA cm-2 with 100 h stability in alkaline seawater. This work provides a new strategy for electrolysis of high entropy spinel oxides in seawater.

The rational design and preparation of adsorbents with superior performance are of great significance in mitigating water pollution caused by heavy metal ions (HMIs). In this work, fluorite tailings were used as the silica source to synthesize mesoporous silica (MSi) through alkali fusion. The resulting MSi was then mixed with calcium oxide to prepare calcium silicate hydrate (CSH) via one-step hydrothermal method. The effects of different hydrothermal temperatures on microstructures and the adsorption properties of CSH were investigated. The changes of CSH crystal structure, microscopic morphology, and surface functional groups were analyzed using XRD, BET, SEM, TEM, and FT-IR. The optimal adsorption conditions for Cr3+ were explored by assessing the influence of initial concentration, contact time, and pH. The results showed that the maximum adsorption capacity of CSH could reach 488.56 mg/g under the hydrothermal temperature of 180 °C, initial concentration of 250 mg/L, contact time of 360 min, and pH of 5.5. Besides, the adsorption kinetics, thermodynamics, and isotherm modeling were proposed to reveal the Cr3+ adsorption mechanism, which demonstrated that the Cr3+ adsorption process is mainly dominated by ion exchange and surface complexation. The novel CSH adsorbent prepared in this work has the advantages of low-cost raw materials, simple preparation process, excellent adsorption performance, and no secondary pollution, which provides a viable route to utilize tailings and obtain valuable HMIs adsorbents.

One of the most challenging problems for people around the world is the lack of clean water. In the past few decades, the massive discharge of emerging organic pollutants (EOPs) into natural water bodies has exacerbated this crisis. Considerable research efforts have been devoted to removing these EOPs due to their biotoxicity at low concentrations. Heterogeneous photocatalysis via coupling clay minerals with nanostructured semiconductors has proven to be an economical, efficient, and environmentally friendly technology for the elimination of EOPs in drinking water and watershed water. Natural zeolite minerals (especially clinoptilolites) are regarded as appropriate supports for semiconductor-based photocatalysts due to their characteristics of having a low cost, environmental friendliness, easy availability, co-catalysis, etc. This review summarizes the latest research on clinoptilolites used as supports to prepare binary and ternary metal oxide or sulfide semiconductor-based hybrid photocatalysts. Various preparation methods of the composite photocatalysts and their degradation efficiencies for the target contaminants are introduced. It is found that the good catalytic activity of the composite photocatalyst could be attributed to the synergistic effect of combining the clinoptilolite adsorbent with the semiconductor catalyst in the heterogeneous system, which could endow the composites with an excellent adsorption capacity and produce more e−/h+ pairs under suitable light irradiation. Finally, we highlight the serious threat of EOPs to the ecological environment and propose the current challenges and limitations, before putting the zeolite mineral composite photocatalysts into practice. The present work would provide a theoretical basis and scientific support for the application of zeolite-based photocatalysts for degrading EOPs.

Electrocatalytic CO2RR is an ideal method. It is capable of converting CO2 into usable fuels and valuable chemical products. Electrocatalytic CO2RR produces a wide range of chemicals. Of these, ethanol (EtOH) is favored for its wide industrial and commercial value. However, electrocatalytic CO2RR preparation of EtOH involves C-C coupling reactions and is a multi-electron transfer process. For this reason, the efficient electrochemical conversion of EtOH by CO2RR remains a great challenge. The preparation of EtOH by electrocatalytic CO2RR involves the interference of a competing hydrogen evolution reaction as well as some other reaction intermediates. This limits the improvement of Faraday efficiency of ethanol (FEEtOH) and the current density of ethanol (JEtOH). To improve ethanol selectivity, the researchers designed and modified the catalysts using engineering regulation effects such as reaction conditions engineering regulation, surface engineering regulation, interfacial engineering regulation, and single atom engineering regulation, and achieved excellent results. Therefore, it is important to understand the key factors affecting the catalyst activity by different engineering regulations and to apply a combination of engineering regulations to the catalyst development. Therefore, this paper firstly provides a comprehensive summary of the catalysts applied for the preparation of EtOH by electrocatalytic CO2RR, including two major categories of catalysts containing pure metal active components and catalysts without pure metal active components. Subsequently, the main effects of engineering modulation on catalyst activity are analyzed and summarized in detail, respectively. Finally, the future challenges and development prospects of electrocatalytic CO2RR for EtOH preparation were highlighted.