Brundabana Naik

Ag‐TiO ₂ nanocomposites containing 1, 3, and 5 wt.% Ag was synthesized via a precipitation‐assisted sol‐gel process followed by chemical reduction and evaluated for visible‐light‐driven reduction of Cr(VI). Structural, morphological, surface chemical, and optical properties were characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), UV‐visible diffuse reflectance spectroscopy (UV‐DRS), and photoluminescence (PL) spectroscopy. The formation of anatase TiO ₂ decorated with well‐dispersed metallic Ag nanoparticles was confirmed. Among all samples, 3 wt.% Ag‐TiO ₂ (AT‐3) exhibited the highest photocatalytic activity, achieving 99.3% Cr(VI) reduction within 120 min under visible‐light irradiation at pH 4. The enhanced performance is attributed to localized surface plasmon resonance (SPR)‐induced visible‐light absorption, efficient interfacial charge separation, and reduced electron‐hole recombination. UV‐DRS analysis showed a decrease in the apparent band‐gap energy from 3.44 eV (TiO ₂ ) to 3.12 eV (AT‐3), which is mainly attributed to SPR and interfacial charge transfer rather than to lattice modification. PL results confirmed suppressed recombination of charge carriers. The hierarchical macro‐mesoporous fibrous structure further enhanced mass transport and surface accessibility. These findings demonstrate the potential of plasmonic Ag‐TiO ₂ photocatalysts for efficient solar‐driven remediation of Cr(VI) in wastewater treatment.

Developing multifunctional heterostructures capable of integrating environmental remediation, solar-to-chemical conversion, electrocatalysis, and chemical sensing within a unified material platform remains a major challenge due to the lack of a common structure–property relationship governing these diverse functionalities. Herein, a 2D/2D MoS2/g-C3N5 heterostructure was rationally engineered via a facile ultrasonic-assisted assembly strategy to construct an electronically coupled heterointerface with accelerated interfacial charge transfer kinetics. Structural, morphological, optical, and electrochemical investigations collectively confirm the intimate integration of MoS2 nanosheets with the g-C3N5 framework, resulting in enhanced visible light absorption, suppressed charge recombination, directional migration, and surface electronic modulation. Importantly, these interfacial electronic features serve as the common mechanistic origin for observed multifunctional behavior. The optimized MC31 (MoS2/g-C3N5 = 3:1) heterostructure exhibits superior solar-light-driven ciprofloxacin (CIP) degradation, predominantly mediated by superoxide (•O2–) radicals, along with enhanced photocatalytic H2O2 generation. The same charge-separation characteristics further promote efficient oxygen evolution electrocatalysis by facilitating rapid interfacial electron transport and favorable surface reaction kinetics. In parallel, the electronically modulated heterointerface enables sensitive fluorescence-based glyphosate sensing through effective charge-transfer-induced fluorescence quenching. Mechanistic investigations suggest that the enhanced multifunctional performance originates from a direct Z-scheme charge transfer pathway established across the MoS2/g-C3N5 interface, which simultaneously preserves strong redox potentials and accelerates spatial carrier separation. This work establishes interfacial electronic engineering as a unifying strategy for designing multifunctional 2D heterostructures capable of coupling photocatalytic, electrocatalytic, and sensing functionalities within a single material platform.

The development of efficient and sustainable photocatalysts for environmental remediation is of significant interest in addressing the rising concerns of pharmaceutical and dye contaminants in aquatic systems. In this work, a Co–Al layered double hydroxide (Co–Al LDH) decorated on a nitrogen-enriched graphitic carbon nitride (g-C₃N₅) nanocomposite (LN) with varying weight ratios (1 : 2, 1 : 1, 2 : 1) was successfully synthesised via a facile solvothermal method followed by ultrasonic exfoliation. The optimised LN2 : 1 catalyst with enhanced photocatalytic behaviour was evaluated for photocatalytic organic pollutant degradation, oxygen reduction reaction (ORR) and antibiotic detection via photoluminescence sensing. The LN2 : 1 nanocomposite achieved the highest degradation efficiency of 93.4% against ciprofloxacin (CIP) and 92.1% against Cresol Red (CR) within 120 minutes under solar irradiation, demonstrating its superior catalytic activity compared to pristine g-C₃N₅ and Co–Al LDH. Furthermore, the composite demonstrated enhanced hydrogen peroxide (H₂O₂) generation of 1903.28 µM L⁻¹ (5.5 times that of g-C₃N₅ and 16.43 times that of Co–Al LDH), which was substantially higher than that of pristine components, indicating its ability to drive reactive oxygen species (ROS)-mediated photocatalytic pathways. Moreover, LN2 : 1 showed the most efficient photoluminescence sensing performance toward ciprofloxacin (CIP), achieving a limit of detection (LOD) of 0.982 ppm and R² of 0.979. The BET surface area analysis demonstrated a 2D nano-platelet-like composite with a higher surface area of 30.647 m² g⁻¹, indicative of a structure with abundant active sites for light harvesting and catalytic activation. Experimental analysis, including electrochemical analysis and radical scavenging tests, indicated the involvement of a Type-II mechanism, which markedly enhances charge carrier separation and utilisation, facilitating the generation of ROS such as superoxide (˙O₂ ⁻) and hydroxyl (˙OH) radicals that drive REDOX processes. This study provides a sustainable photocatalytic strategy with the potential to tackle real-world environmental challenges by enabling efficient degradation of emerging contaminants and advancing water purification technologies.

The efficient removal of persistent organic pollutants and toxic heavy metals from water and sustainable chemical synthesis remain a critical environmental challenge. In this study, an oxygen vacancy-BiVO₄@g-C₃N₅ (BC1:3) core-shell hybrid photocatalyst was developed, leveraging visible-light-mediated photocatalysis as a green and scalable solution. The unique core-shell architecture facilitates enhanced charge separation and transfer at the heterojunction interface, significantly improving the photocatalytic efficiency. BC1:3, synthesized via a simple hydrothermal-calcination process, showed remarkable ciprofloxacin degradation activity, reaching a rate constant of 0.0155 min^-1 i.e., 90.2%, which is 1.38 times greater than g-C₃N₅ (CN) and 1.7 times greater than BiVO₄ (BVO), this performance further elevated to 95.12% in connection to an external oxygen purging, primarily attributed to the enhanced activation of reactive oxygen species (ROS) under elevated oxygen concentration. The catalyst also demonstrated excellent Cr (VI) photoreduction performance (0.016 min^-1), approximately 2.66 and 1.7-fold higher than BVO and CN, respectively. Furthermore, BC1:3 achieved remarkable H₂O₂ generation (1824.44 μM L^-1), outperforming BVO and CN by factors of 19 and 8.5 times, respectively, which can be ascribed to the efficient charge separation and accelerated two-electron oxygen reduction pathway facilitated by the Z-scheme heterojunction. Reactive species analysis confirmed the involvement of ^•O₂ ^-, ^•OH, and photogenerated h⁺ as major contributors to its photocatalytic activity. The visible-light-driven Z-scheme heterojunction between the BVO and CN extended light absorption and promoted efficient charge carrier dynamics. The catalyst demonstrated excellent stability and reusability, underscoring its potential as a robust photocatalyst for advanced water treatment and green chemical production.

An organic C-N polymeric nanocomposite, g-C₃N₄/g-C₃N₅ sheet (ECN45), was designed through thermal polymerization, followed by KBr-assisted exfoliation, to investigate its potential as a photocatalyst for the photodegradation of organic antibiotic pollutants and antimicrobial activities. Graphitic carbon nitride (g-C₃N₄) is a 2D material recognized as a highly promising photocatalyst; however, it possesses an elevated frequency of photogenerated electron-hole pair recombination and a constricted absorption range for visible light of up to 450 nm. Therefore, the formation of a heterojunction of 1D g-C₃N₅ upon g-C₃N₄ can minimize the charge recombination of g-C₃N₄. Furthermore, due to a lack of sufficient surface activation, the bulk composite (BCN45) was exposed to KBr exfoliation, resulting in a g-C₃N₄/g-C₃N₅ sheet (ECN45). The 1D/2D hybrid catalyst exhibits a reduction in band gap of up to 1.81 eV due to the presence of azo linkages and π-conjugated bonds compared to its pristine elements. The nanocomposite shows a red shift toward the visible light spectrum compared to its pristine forms. The morphological, spectroscopic, and physicochemical investigations of the nanocomposite are confirmed by TEM, SEM-EDX, BET, XRD, UVDRS, FTIR, XPS, PL, and electrochemical analysis techniques. The photocatalytic application is shown by the composite for degrading the antibiotic CIP (ciprofloxacin) for about 93.1% at an acidic environment of pH 3 at its lowest concentration of 10 mg L^-1 in 120 min. Further, the catalyst is examined to show antimicrobial action against Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphylococcus aureus (S. aureus) with the help of the inhibition zone test, MIC (minimum inhibition concentration), and photocatalytic cellular leakage of the microbial body. Also, the plausible Z-scheme mechanisms exhibited by the formed 2D/1D heterostructure for CIP degradation and antimicrobial activity are explained. The enhanced photoactivity is attributed to the synergistic effects of 1D/2D hybrid nanostructure, extended conjugation leading to enriched light harvesting, and Z-scheme heterojunction for better photogenerated charge separation. This approach makes grounds to establish an effective metal-free composite showing efficient photocatalytic activity.

Photocatalysis represents a sustainable approach for cleaner energy production, wastewater treatment, and antimicrobial disinfection. Creating effective photocatalysts that respond to visible light is crucial for tackling worldwide challenges related to energy and the environment. Here, for the first time, we have reported a facile solvothermal strategy for the in situ growth of ZnIn₂S₄ nanoflowers on g-C₃N₅ nanoflakes, where the latter were synthesized via thermal polymerization followed by ultrasonic exfoliation. The resulting ZnIn₂S₄/g-C₃N₅ (ZCN-10) composite demonstrated outstanding photocatalytic activity, achieving 88.4% degradation of ciprofloxacin within 90 minutes under solar irradiation and producing 3368 μM L⁻¹ of H₂O₂ under visible light. This enhanced performance when compared to pristine ZnIn₂S₄ and g-C₃N₅ is attributed to the formation of a direct Z-scheme heterojunction, which promotes efficient charge separation, broadens light absorption, and optimizes the band structure and morphology. The ZCN-10 catalyst maintained high photocatalytic efficiency over four consecutive cycles and also exhibited notable antimicrobial activity, producing a 17 mm inhibition zone against B. subtilis and 30 mm inhibition zone against E. coli. Comprehensive analytical characterization confirmed the successful synthesis and structural integrity of the nanocomposite. Mechanistic studies, including radical scavenging and band structure analysis, revealed that the direct Z-scheme configuration significantly enhances charge carrier separation and utilization, facilitating the generation of reactive species such as superoxide (˙O₂ ⁻) and hydroxyl (˙OH) radicals, which drive advanced oxidation processes (AOPs). This work highlights a promising route for developing earth-abundant, eco-friendly photocatalysts for environmental remediation and sustainable energy applications.