Yumei Long

Solar-driven interfacial water evaporation has been recognized as an effective measure to address freshwater scarcity. Photothermal materials lie at the core of this process and have been extensively studied. However, conventional carbon-based materials typically suffer from high thermal emissivity, leading to significant heat loss. Here, we report a tungsten carbide/carbon composite polyvinyl alcohol hydrogel evaporator (PWC) for solar-driven interfacial seawater evaporation. Specifically, a tungsten carbide/carbon (WC/C) composite was synthesized via a straightforward one-step molten salt coating method and exhibited a remarkable photothermal conversion efficiency of 67.1%, attributed to the plasmon resonance absorption effect of WC nanoparticles. When incorporated into a polyvinyl alcohol (PVA) hydrogel via a physical-chemical dual-crosslinking strategy, the resulting PWC evaporator achieved a high evaporation rate of 2.99 kg m⁻² h⁻¹ and a conversion efficiency of 90.9% in a 5 wt% NaCl solution under 1 kW m⁻² illumination. In addition, the evaporator can purify seawater and effectively remove a variety of organic dyes. This study provides a viable strategy for a sustainable freshwater supply.

Solar-driven interfacial evaporation has emerged as a promising technology for freshwater production and energy sustainability. It leverages solar energy to efficiently evaporate water, enabling sustainable seawater desalination and wastewater purification. However, designing efficient evaporators that combine rapid water transport and high salt resistance remains a significant challenge. Drawing inspiration from the long-range ordered vasculature and anti-gravity water management mechanisms of taro stem, we fabricated a biomimetic aerogel featuring vertically aligned microchannels through a unidirectional freezing ice templating method. The aerogel integrates a core–shell SiC@C composite as a high-performance photothermal converter, a mechanically robust PVA/PAM double network forming the channel walls, and hydroxyapatite (HA) nanorods serving as both a thermal insulation skeleton and a mechanical reinforcement. In contrast to conventional aerogels with randomly oriented and tortuous pores, the biomimetic honeycomb architectures with vertically aligned channels endow the material with exceptional water transportation, thereby facilitating efficient salt ion diffusion and mitigating salt crystallization. Under 1 sun illumination (1 kW m⁻²), the aerogel achieves a high evaporation rate of 3.24 kg m⁻² h⁻¹, substantially outperforming most reported evaporators with disordered porous structures. The unique vertical channel configuration ensures continuous and stable desalination performance, highlighting its great potential as an effective solution to address global freshwater scarcity.

As an environmentally friendly and clean energy technology, solar-driven interfacial evaporation technology has attracted wide attention. However, organic pollutants can easily pollute distilled water during the evaporation of wastewater. In this work, we report a strategy of N-TiO₂/C solar absorption with a low bandgap (2.33 eV), excellent light absorption ability, and high photothermal conversion efficiency (48.2%). Black N-TiO₂/C was prepared by the sol-gel method in the presence of hexamethylenetetramine as a source of nitrogen and carbon. The simultaneous N doping and C with superior photothermal effect rapidly increased the surface temperature of the material, reduced the recombination rate of electrons and holes, and improved the photocatalytic activity, showing great potential for solar thermal energy conversion. The prepared solar absorbent and polyurethane (PU) were mixed evenly to form a porous N-TiO₂/C/PU (NTCP) foam for purifying water. The evaporator produced clean water at a rate of 1.73 kg m⁻² h⁻¹ under the simulated sunlight of 1 sun irradiation. Meanwhile, the evaporator simultaneously photodegraded methylene blue (MB) and rhodamine B (RhB) underwater at a removal rate > 90%. The bifunctional solar water evaporation device combining photocatalytic and photothermal effects holds great potential for water purification.

Currently, accurate quantification of antibiotics is a prerequisite for health care and environmental governance. The present work demonstrated a novel and effective electrochemical strategy for chloramphenicol (CAP) detection using carbon-doped hexagonal boron nitride (C-BN) as the sensing medium. The C-BN nanosheets were synthesized by a molten-salt method and fully characterized using various techniques. The electrochemical performances of C-BN nanosheets were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the electrocatalytic activity of h-BN was significantly enhanced by carbon doping. Carbon doping can provide abundant active sites and improve electrical conductivity. Therefore, a C-BN-modified glassy carbon electrode (C-BN/GCE) was employed to determine CAP by differential pulse voltammetry (DPV). The sensor showed convincing analytical performance, such as a wide concentration range (0.1 µM–200 µM, 200 µM–700 µM) and low limit of detection (LOD, 0.035 µM). In addition, the proposed method had high selectivity and desired stability, and can be applied for CAP detection in actual samples. It is believed that defect-engineered h-BN nanomaterials possess a wide range of applications in electrochemical sensors.

Regulating the heterostructure of electrode materials has a great influence on electron migration and subsequent electrochemical reactions, which play a critical role in the sensing process. Herein, a facile method has been demonstrated to synthesize TiN/graphitic carbon (TiN/gC) nanocomposites by the in situ growth of TiN nanoparticles on C nanosheets. The formation of TiN/gC heterojunctions was evidenced by X-ray diffraction (XRD), Raman microscopy and transmission electron microscopy (TEM). This heterostructure can effectively facilitate electron transfer and increase the electrochemically active area, which improves the electrocatalytic performance. Interestingly, the TiN/gC-modified glassy carbon electrode (TiN-gC/GCE) exhibited excellent electrocatalytic activity toward ofloxacin (OFLX) redox. With the change in the OFLX concentration, the electrochemical response of the sensor also changes. By using a differential pulse voltammetry (DPV) technique, the designed sensor showed a wide detection range: the DPV response was linearly dependent on the concentrations in the range of 0.05 – 1.0 and 1.0 – 100 μ M. Moreover, TiN-gC/GCE demonstrated outstanding analytical performances in the quantitative OFLX assay, such as a high sensitivity of 2876 μ A·mM ⁻¹ ·cm ^–2 , low detection limit of 0.016 μ M, good selectivity and stability. The proposed method was successfully applied for OFLX detection in eye drops and environmental water with satisfactory results.

A new strategy has been developed for the determination of trace lead ions (Pb²⁺) based on hexagonal boron nitride (h-BN) laden with point defect. The defect-laden boron nitride (D-BN) was synthesized by a thermal polymerization route, in which melamine borate was used as a precursor. The defect microstructure was confirmed by photoluminescence (PL) and x-ray diffraction (XRD) techniques. As compared with h-BN, the D-BN-modified glassy carbon electrode (GCE) showed an enhanced electrochemical response towards Pb²⁺ peaking at − 0.551 V (vs. SCE), which was evidenced by linear sweep anodic stripping voltammetry (LSASV) results. The point defect plays a pivotal role in the electrocatalytic reaction process, which can mediate the electronic structure and surface properties of h-BN. Accordingly, the sensor presented a low detection limit of 0.15 μg/L towards Pb²⁺ and a wide linear response concentration range from 0.5 to 400 μg/L (correlation coefficient = 0.995). In view of its superior selectivity, stability, and reproducibility, the proposed method was applied for Pb²⁺ determination in real samples and exhibited satisfactory results. This work provides insight for the construction of electrochemical sensor with high-performance by engineering defects of modifying materials. Graphical abstract Defect-loaden h-BN exhibited enhanced electrocatalytic redox reaction towards lead ions and thus a novel Pb²⁺ sensor with high performances was constructed.

An electrochemical sensor is described for the simultaneous determination of hydroquinone (HQ) and catechol (CC) based on a nanocomposite consisting of gold nanoparticles and graphitic carbon nitride (g-C₃N₄). The nanocomposite was synthesized via one-step thermal polymerization route and characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared techniques. The results confirmed the close contact between gold nanoparticles and g-C₃N₄. The nanocomposites exhibited the enhanced electrocatalytic redox towards HQ and CC. A glassy carbon electrode was modified with the nanocomposite to obtain a sensor that exhibited favorable analytical properties in the simultaneous detection of HQ and CC, with voltammetric peaks typically near −0.14 and − 0.02 V (vs. saturated calomel electrode). Linear responses are found between 1.0 and 320 μM for HQ (with a 0.3 μM detection limit; at S/N = 3), and between 0.1 and 320 μM for CC (with a 0.04 μM detection limit; at S/N = 3). The sensor was applied for the simultaneous determination of HQ and CC in spiked water samples, and acceptable recoveries were achieved. The superior sensing properties of the electrode are attributed to the synergy between the microstructure (heterojunction and porosity) and the π interactions between phenolic isomers and g-C₃N₄.

The authors describe the preparation of amino-functionalized carbon dots (NH₂-CDs) via a one-step hydrothermal process using silver nitrate and chitosan as the precursors. The NH₂-CDs have a fairly consistent size distribution with an average size of 2.8 ± 0.5 nm. This is attributed to the introduction of Ag(I) both as a catalyst and a precipitant. The NH₂-CDs are highly crystalline. Their surface carries amino groups and carboxy groups which is confirmed by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Horseradish peroxidase (HRP) was immobilized in the NH₂-CDs and then placed on a glassy carbon electrode (GCE). Spectroscopic and electrochemical analyses evidenced the stability and good bioactivity of the immobilized HRP. This reveals that NH₂-CD is a desirable matrix for enzyme immobilization. The modified GCE exhibits enhanced electro-catalytic activity towards hydrogen peroxide (H₂O₂) reduction as compared to that of plain CDs. The effects of pH value and loading on the performances of the modified GCEs were studied. Under optimized conditions, the biosensor has a linear response in the 5 to 590 nM H₂O₂ concentration range, with a 1.8 nM defection limit (at an S/N ratio of 3). The sensor is stable, reproducible and selective. Finally, the sensor was applied to determine H₂O₂ in real samples, and satisfactory recoveries were achieved.