Surface Active Sites Research Articles

Revealing the Nature of Cyano Groups Modified K, O Codoped Graphitic Carbon Nitride Toward Optimized Photocatalytic H2 and H2O2 Evolution.

The rapid charge separation and adequate surface-active sites are key points for photocatalytic H2 and H2O2 evolution simultaneously. Here, cyano groups modified K, O codoped graphitic carbon nitride (KOCCN-X) is prepared through a thermal polymerization process utilizing KOH and urea as precursors. The resultant KOCCN-X exhibits obviously increased H2 and H2O2 evolution, and the KOCCN-0.5 demonstrates the optimal photocatalytic performance, achieving H2 and H2O2 production rates of 4.58 and 3.56mmol g-1h-1, which are ≈7.9 and 6.5 times higher than pristine g-C3N4 (CN), respectively. The structural analysis proves that K is doped at the layers of CN to form interlayer bridging via K-N coordination. O atom substitutes the N atom within the C─N═C bond in the formation of C─O─C linkage, and the cyano group is located at the edge of CN. Theoretical and experimental analysis ascertain that the interlayer bridging via K-N coordination acts as efficient electron migration channels, O and cyano groups can serve as active sites for H2O2 and H2 production, respectively. The synergistic interplay between K, O, and cyano groups effectively boosts the photocatalytic H2O2 and H2 performance. This study provides novel insights into the development of CN-based photocatalysts that can concurrently generate H2 and H2O2.

Shining Light on Hydrogen: Solar-Powered Catalysis with Transition Metals.

Artificial photosynthesis offers a promising pathway to address environmental challenges and the global energy crisis by converting solar energy into storable chemical fuels such as hydrogen. Among various photocatalysts, transition metal-based materials have garnered significant attention due to their tunable crystal phase, morphology, surface active sites, and other key properties. This review provides a comprehensive overview of recent advances in transition metal-based photocatalysts for hydrogen production, with a particular focus on modification strategies and their underlying mechanisms. By systematically classifying these materials, this work highlights effective approaches for enhancing their catalytic performance, including structural engineering, electronic modulation, and interfacial optimization. Furthermore, this work discusses the fundamental principles governing these modifications, offering deeper insights into their roles in charge separation, surface reactions, and stability. Finally, this work outlines future research directions and key challenges in the rational design of highly efficient transition metal-based photocatalysts for sustainable hydrogen production.

Biopermissible and Hydrophilic G-CNNPs for Noncooperative Binding with Picomolar of Cancer Drug Etoposide and Photodynamic Therapy.

Etoposide (ETO), a chemotherapeutic agent for lung cancer, requires precise and prompt detection to optimize cancer management and mitigate toxicity. In this study, we present a scalable solid-state methodology for the synthesis of highly hydrophilic (average contact angle 10.73°) graphitic carbon nitride nanoparticles (g-CNNPs) employing urea and trisodium citrate. The synthesized g-CNNPs possess six surface active sites, enabling their function as effective fluorescence sensors for detecting the lung cancer drug ETO at physiological pH. The g-CNNPs demonstrate high selectivity and sensitivity for ETO detection (ΦF 20.29 → 17.95%), with a detection limit (LoD) of 95 pM (R2 = 0.99144), quantification limit (LoQ) of 310 pM, and an association constant (Ka) of 1.0162 M-1. The fluorescence quenching of g-CNNPs by ETO is attributed to intermolecular hydrogen bonding, characterized by static quenching and a noncooperative binding mechanism within the g-CNNPs·ETO complex. Additionally, time-correlated single photon counting (TCSPC) analysis confirms the static quenching of g-CNNPs (lifetime 5.175 → 5.281 ns) upon ETO detection. The formation of the g-CNNPs·ETO complex is verified through DFT studies and a range of physicochemical characterization techniques, including XRD, FE-SEM, HR-TEM, XPS, Raman, FT-IR, and UV-vis. The developed detection method proved effective in identifying ETO in urine samples, achieving high recovery rates between 95.45% and 110.78%. To evaluate their biological efficacy, a series of experiments were conducted, including MTT cytotoxicity assays against mouse fibroblast cell lines L929, the anticancer activity of g-CNNPs toward HT29 cells (with and without light exposure), and ROS generation. Collectively, the results from these real samples and biological studies affirm that biopermissible g-CNNPs are promising candidates for clinical trials.

High-Efficiency Biodiesel Production Using ZnO-Modified Starfish-Based Catalysts

This study introduces a novel approach to biodiesel production by repurposing starfish, an abundant marine waste, as a sustainable catalyst material. Starfish, primarily composed of Ca-Mg carbonate, were calcined to produce calcium oxide (CaO) and magnesium oxide (MgO), which were subsequently doped with varying zinc loadings through hydrothermal treatment. This innovative use of marine waste not only addresses environmental concerns but also provides a cost-effective catalyst source. Among the tested compositions, the catalyst doped with 10 wt% Zn achieved the highest biodiesel yield of 96.6%, outperforming both lower and higher Zn loadings. Zinc incorporation significantly improved the catalyst’s surface area, pore volume, and active site density, as confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) surface analysis. These enhancements facilitated a biodiesel yield of 96.6% within 10 h, a substantial increase compared to the undoped catalyst (86.5%) under identical conditions. Reusability tests further confirmed the catalyst’s high activity over three consecutive cycles, with yields of 96.6%, 94.2%, and 86.5%, respectively, while SEM-EDS analysis demonstrated effective Zn retention after repeated use. This study demonstrates a pioneering strategy for transforming marine waste into a high-performance catalyst, paving the way for sustainable biodiesel production.

Interface Engineering, Charge Carrier Dynamics, and Solar-Driven Applications of Halide Perovskite/2D Material Heterostructured Photocatalysts.

Halide perovskites (HPs), renowned for their intriguing optoelectronic properties, such as robust light absorption coefficient, long charge transfer distance, and tunable band structure, have emerged as a focal point in the field of photocatalysis. However, the photocatalytic performance of HPs is still inhibited by rapid charge recombination, insufficient band potential energy, and limited number of surface active sites. To overcome these limitations, the integration of two-dimensional (2D) materials, characterized by shortened charge transfer pathways and expansive surface areas, into HP/2D heterostructures presents a promising avenue to achieve exceptional interfacial properties, including extensive light absorption, efficient charge separation and transfer, energetic redox capacity, and adjustable surface characteristics. Herein, a comprehensive review delving into fundamentals, interfacial engineering, and charge carrier dynamics of HP/2D material heterostructures is presented. Numerous HP/2D material photocatalysts fabricated through diverse strategies and interfacial architectures are systematically described and categorized. More importantly, the enhanced charge carrier dynamics and surface properties of the HP/2D material heterostructures are thoroughly investigated and discussed. Finally, an analysis of the challenges faced in the development of HP/2D photocatalysts, alongside insightful recommendations for potential strategies to overcome these barriers, is provided.

Graphitic Carbon Nitride Nanomaterials-Based Electrochemical Sensing Interfaces for Monitoring Heavy Metal Ions in Aqueous Environments.

The persistent threat of heavy metal ions (e.g., Pb2+, Hg2+, Cd2+) in aqueous environments to human health underscores an urgent need for advanced sensing platforms capable of rapid and precise pollutant monitoring. Graphitic carbon nitride (g-C3N4), a metal-free polymeric semiconductor, has emerged as a revolutionary material for constructing next-generation environmental sensors due to its exceptional physicochemical properties, including tunable electronic structure, high chemical/thermal stability, large surface area, and unique optical characteristics. This review systematically explores the integration of g-C3N4 with functional nanomaterials (e.g., metal nanoparticles, metal oxide nanomaterials, carbonaceous materials, and conduction polymer) to engineer high-performance sensing interfaces for heavy metal detection. The structure-property relationship is critically analyzed, emphasizing how morphology engineering (nanofibers, nanosheets, and mesoporous) and surface functionalization strategies enhance sensitivity and selectivity. Advanced detection mechanisms are elucidated, including electrochemical signal amplification, and photoinduced electron transfer processes enabled by g-C3N4's tailored bandgap and surface active sites. Furthermore, this review addresses challenges in real-world deployment, such as scalable nanomaterial synthesis, matrix interference mitigation, and long-term reliable detection. This work provides valuable insights for advancing g-C3N4-based electrochemical sensing technologies toward sustainable environmental monitoring and intelligent pollution control systems.

Ab Initio Study on Doped Cu138X2 Nanoparticles with dispersed surface active sites for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

Copper nanoparticles (NPs) exhibit significant potential in electrocatalysis owing to their tunable electronic structure and abundant surface‐active sites. However, the multifaceted complexity of Cu‐based nanoparticles induced by heteroatom dopants fundamentally limits our ability to decipher the nitrate‐to‐ammonia electroreduction (NO3RR) mechanism, creating a critical knowledge gap that obstructs the targeted engineering of advanced catalysts with atomic precision. In this study, we employed first‐principles calculations to design a series of highly surface‐dispersed transition metal‐doped Cu138X2 (X = Ag, Au, Pd, Zn) bimetallic electrocatalysts for nitrate reduction to ammonia, based on the structure of Cu140 NPs. Theoretical analysis revealed that Cu138Au2 exhibits significant advantages in NO3RR, with a remarkably low limiting potential of ‐0.20 eV. Additionally, significant energy barriers were observed for the formation of by‐products NO and NO2 on Cu138Au2, ensuring high selectivity towards ammonia. For Cu‐based catalysts, we propose that the *NO2 → *HNO2 step is critical and can serve as a descriptor for rapid screening of Cu‐based catalysts. This study not only provides important insights into the research of Cu NPs as NO3RR electrocatalysts but also establishes a theoretical foundation for enhancing their catalytic performance through surface modification or compositional tuning.

Carbon Dot-Based Biosensors for Continuous Glucose Monitoring in Point-of-Care Devices: Advancements, Challenges, and Future Prospects

Continuous glucose monitoring (CGM) is crucial for managing diabetes and food/pharmaceutical quality control because of the clinical and industrial relevance of glucose. Various electrochemical and optical techniques have been explored for the detection of glucose. Carbon dots (CDs), nanomaterials with high surface areas and active sites, show promise as nanozymes for CGM because of their tunable size, shape, and surface properties. This review critically evaluates the impact of CD oxidation states and surface residues on the sensitivity and selectivity of CGM. CD nanocomposites incorporating metals, metal oxides, and metal sulfides were also assessed. Special focus is placed on advancing the performance of next-generation CGM systems in terms of efficiency and reliability. The interactions between CDs and various composite configurations were examined to identify opportunities for enhancing current CGM technologies. This comprehensive analysis of the evolving biosensor landscape aims to provide insights that support innovation in glucose monitoring for patient care and industrial applications.

Anion-cation dual-doping strategy induced electronic structure regulation of sulfide to enhance hydrogen evolution reaction at high current density.

Anion-cation dual-doping strategy induced electronic structure regulation of sulfide to enhance hydrogen evolution reaction at high current density.

Fabrication of a sustainable in-situ iron-carbon micro-electrolysis cell from landfill leachate for the purification of mercury-contaminated wastewater and vital mechanism

Fabrication of a sustainable in-situ iron-carbon micro-electrolysis cell from landfill leachate for the purification of mercury-contaminated wastewater and vital mechanism

Cellulose/covalent organic framework aerogel for efficient removal of Cr(VI): Performance and mechanism study.

Cellulose/covalent organic framework aerogel for efficient removal of Cr(VI): Performance and mechanism study.

Furfural to 2-Methylfuran via Transfer Hydrodeoxygenation using 2-Pentanol over Cu-ZnO Nanowires: Extraction of Furfural and its Conversion to 2-Methylfuran

The extraction of furfural from an aqueous solution and its conversion to 2-methylfuran through transfer hydrodeoxygenation (THDO) have been successfully carried out using a Cu-ZnO (30:70) catalyst in the vapour phase, utilizing 2-pentanol as extraction solvent and hydrogen. Due to the lower temperature of the reaction, the yield of 2-methylfuran and 2-pentanone was 83% and 90%, respectively. The carbon balance concerning furfural was >90%, which is higher than that of direct hydrodeoxygenation of furfural. The activity of catalyst and the yield of 2-methylfuran are associated with the number of surface active sites (Cu0/Cu+), as the high loading of catalyst produced a high yield of 2-methylfuran. The stability of the catalyst was studied for 23 h at 250 ºC and found to have stable activity. Moreover, the Lewis acidity of Zn2+ facilitates the process more easily and the final catalyst generated from aurichalcite is responsible for the increased number of copper sites on the catalyst’s surface. Moreover, XPS analysis also proved the presence of more surface Cu0 species and CHNS analysis confirmed the coke resistance of the Cu-ZnO catalyst.

Scheelite Catalysts for Thermal Mineralization of Toluene: A Mechanistic Overview.

Toluene, a highly stable aromatic hydrocarbon, is utilized as a benchmark molecule for thermal mineralization by the catalytic community. Mostly, the catalysts used for toluene mineralization either use platinum group metals (PGM) as catalysts or are regulated by a plasma incinerator. Though these catalysts/processes promise better efficiency and lower reaction temperature, they are neither cost-effective nor do they produce thermally stable byproducts. However, most of the metal-oxide catalysts used for toluene degradation are less efficient owing to incomplete mineralization and formation of stable intermediates, which results in higher mineralization temperature. The present work showcases tungsten- and molybdenum-based Scheelites [BaXO4 (X = W, Mo, and Mo0.5W0.5)], which have been utilized for toluene mineralization at ∼200 °C. The intermediates formed during adsorption and thermal reaction are deciphered as a function of temperature using in situ FT-IR studies including their kinetic behavior. These surface intermediates formed over the Scheelite catalysts under an oxidative/inert atmosphere elucidate the toluene mineralization mechanism as a function of temperature/time. The surface active sites for these oxide catalysts for both adsorption and formation of reaction intermediates are deciphered using detailed X-ray photoelectron spectroscopy (XPS) studies. It shows the effective role of the oxidation states of constituent oxides M-O (M = Mo/ W) in the reaction mechanism. Mineralization of toluene in a nonoxidative atmosphere shows a Mars and Van Krevelen (MVK) type of mechanism, suggesting participation of lattice oxygen for the catalytic reaction. To the best of our knowledge, this work represents one of the lowest temperatures achieved for toluene mineralization using oxide catalysts. The identification of reaction intermediates can guide further optimization efforts to minimize the mineralization temperature.

Activating H3O+ Intercalation Chemistry in Aqueous Zn-VO2(B) Batteries via Tungsten Doping and Oxygen Vacancies.

Vanadium-based materials have shone brightly in aqueous Zn metal batteries due to their high theoretical capacity and excellent high-rate capability. However, the severe vanadium dissolution attacked by H+ during cycling has persistently resulted in unsatisfactory cycling stability at low current density (generally ≤0.5Ag-1). To address this critical issue, a reversible H3O+ intercalation chemistry in tunnel-structured VO2(B) materials is herein reported, which is activated by disordered substitution doping of V4+ by W5+/6+ ions while simultaneously introducing oxygen vacancies. Both experiments and theoretical calculations demonstrate that H3O+ exhibits stronger adsorption energy on the (110) plane of synthesized W0.05V0.95O1.94(B) electrode than H+. Moreover, the synergy between W5+/6+ dopants and oxygen vacancies can effectively improve the distribution of adsorption sites for H3O+, contributing to an enhanced utilization of surface-active sites. As a result, this cathode chemistry delivers a high specific capacity of 407mAhg-1 at 0.1Ag-1 and maintains 357mAhg-1 with almost no capacity decay after 100 cycles at 0.5Ag-1. These findings offer a promising pathway for developing rechargeable long-life vanadium-based cathodes.

Hollow MOF‐derived layered NiS2/Mxene composites for high‐performance supercapacitors

MXene, characterized by its unique layered structure, shows great promise as an electrode material for energy storage devices. MXene‐based electrode materials, with their excellent metallic conductivity, high packing density, and large specific surface area, efficiently store high‐rate Faradaic pseudocapacitive energy. This study successfully synthesized a layered NiS2/Mxene composite using a self‐assembly method. The structural design significantly increases the composite material’s specific surface area and active sites while effectively suppressing the restacking of MXene nanosheets. Furthermore, the MXene layer wrapped around NiS2 not only improves electrical conductivity but also stabilizes the hollow structure to prevent collapse. Test results reveal that the NiS2/Mxene composite demonstrates a specific capacitance of 1016 F g‐1 at a current density of 1 A g‐1. The asymmetric supercapacitor (ACS) achieves an energy density of 46.6 Wh kg‐1 at a power density of 698.7 W kg‐1, with excellent cycling stability. This study proposes a novel design strategy for asymmetric supercapacitor electrodes incorporating MOFs and MXene composites.

Elimination of patulin in apple juice using cysteine capped Fe3O4 nanoadsorbent

The present study evaluated the preparation of L-cysteine capped Fe3O4 (magnetite) nanoparticles (LCys-Fe3O4 NPs), with a particular focus on their potential as an adsorbent and also the efficiency of these NPs in the removal of patulin from apple juice. The methods employed, including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray powder diffraction analysis (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FT-IR), effectively showed the synthesis of LCys-Fe3O4 NPs. The proposed method was not only used for patulin removal; rather, it significantly enhanced the sensitivity of patulin measurement. The efficiency of patulin elimination was affected by many factors, including contact time (5–140 min), patulin initial concentration (50–150 µg/L), and amount of NPs (1–5 mg). The synthesized adsorbent achieved a removal efficiency of 98.6% for patulin adsorption at pH = 3.8. This was accomplished by employing 3 mg LCys-Fe3O4 NPs over a 100-min duration, resulting in a maximum adsorption capacity of 454 µg/g for the initial concentration of patulin 50 µg/L. This high removal efficiency can be attributed to active surface sites (–NH2 and –COOH groups). The removal information obtained from an HPLC method, using the prepared adsorbent, exhibited a good fit with the Freundlich isotherm, indicating a multi-layer adsorption process on the adsorbent. The experimental findings were analyzed using an adsorption kinetic model, revealing that the adsorption kinetics of patulin onto LCys-Fe3O4 NPs conformed to the pseudo-second-order model. In conclusion, the proposed method demonstrated remarkable efficacy in decreasing patulin concentrations in contaminated apple juice by approximately 81.5%. Moreover, the adsorption process had no impact on the quality of the apple juice.

High performance carbon matrix and aqueous zinc ion hybrid capacitors were prepared from waste biomass cotton fiber.

High performance carbon matrix and aqueous zinc ion hybrid capacitors were prepared from waste biomass cotton fiber.

One-Pot Synthesis of Pd@Pt Core-Shell Icosahedron for Efficient Oxygen Reduction.

Enhancing the limited utilization and overall yield of Pt-based catalysts is essential for advancing proton exchange membrane fuel cell technology. Herein, we report a facile one-pot method that utilizes TEG as both a solvent and a reductant to efficiently synthesize a Pd@Pt core-shell icosahedron. By controlling the surface energy between Pd and Pt precursors, we achieved the formation of Pd@Pt core-shell icosahedra, resulting in a fourfold reduction in reaction time and an eightfold increase in yield. Moreover, the core-shell structures exhibited a significant enhancement in electrocatalytic activity, stability, and Pt utilization efficiency. In comparison to commercial Pt/C, the Pd@Pt core-shell icosahedron exhibited efficient mass activity (MA, 1.54 A mg-1Pt) and specific activity (SA, 2.24 mA cm-2Pt) at 0.9 V (vs. RHE), while demonstrating excellent stability with minimal loss of activity even after 10,000 potential cycles. The Pd@Pt icosahedra configuration integrates the advantages of multiply twinned nanostructures, leading to rich electrochemical active surface sites and fast charge transport, thereby improving its catalytic performance and long-term stability during electrocatalytic reactions.

Highly Active Oxygen Evolution Integrating with Highly Selective CO2-to-CO Reduction

Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation. However, the sluggish kinetics of oxygen evolution reaction (OER) and poor selectivity of CO2 reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels. Herein, we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode. More specifically, the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes, resulting in one of the highest OER activities of 6.51mAcm-2 (1.23 VRHE, AM 1.5G). Additionally, single-atom cobalt (II) phthalocyanine anchoring on the N-rich carbon substrates to increase Co-N coordination number remarkably promotes CO2 adsorption and activation for high selective CO production. Their integration achieved a record activity of 109.4μmolcm-2h-1 for CO production with a faradaic efficiency of > 90%, and an outstanding solar conversion efficiency of 5.41% has been achieved by further integrating a photovoltaic utilizing the sunlight (> 500nm).

Fe-doped carbon dots with enhanced fluorescence: Facilitating Cu2+ detection and urea electro-oxidation.

Fe-doped carbon dots with enhanced fluorescence: Facilitating Cu2+ detection and urea electro-oxidation.