Multi-Walled CNTs/BiVO4 Heterostructures for Solar-Driven Evaporation System and Efficient Photocatalytic Activity against Oxytetracycline.

Developing a sustainable environment requires addressing primitive water scarcity and water contamination. Antibiotics such as oxytetracycline (OTC) may accumulate in the environment and in the human body, increasing the risks to the ecosystem. The treatment of polluted water and the production of potable water can be achieved in a variety of ways, including photodegradation, solar distillation, and filtration. Freshwater supplies can be increased by implementing energy-efficient technologies for the production of clean water. Solar water evaporation combined with photocatalytic degradation and sterilization offers a promising avenue for integration into the clean water and energy production fields. The present study reports the synthesis of a 3D solar steam generator comprised of BiVO4 and carbon nanotubes (CNT) nanocomposite decorated over a cigarette filter as the light-to-heat conversion layer for solar steam generation. The BiVO4@CNT-based 3D solar evaporator over the hydrophilic cellulosic fibers of the cigarette filter endowed excellent evaporation rates (2.36 kg m-2 h-1) under 1 kW m-2 solar irradiation, owing to its superior hydrophilicity and broadband solar absorption (96%) equipped with localized heating at microscale thermal confinement optimized by the minimum thermal conductivity of the overall system. Furthermore, the BiVO4@CNT composite exhibited a heightened photo activity up to 83% of the photodegradation of oxytetracycline (OTC) antibiotic due to the inhibition of charge recombination from the industrial effluents. This approach transforms the water-energy nexus into a synergistic bond that offers opportunities to meet expected demand, rather than being competitive.

Optimizing oxygen vacancies and electrochemical performance of CeO2-δ nanosheets through the combination of di- and tri-valent doping.

Ceramic fuel cells presently hold an important position in the future of sustainable energy. However, new concepts and designs are vital for each individual cell's component materials to improve the overall power output and stability. The limited ionic conductivity of the electrolyte component is one major challenge among these. In the present work, we developed nanosheets with a cubic fluoride structure of CeO2 and introduced the di- and tri-valent doping of La and Sr to study their impact on oxygen vacancies and its ionic transport, keeping in mind the fact that CeO2 is reduced when exposed to a reducing atmosphere. The attained La- and Sr-doped fluorite structures of CeO2 exhibited good ionic conductivity of >0.05 S cm-1 at low temperature, and their use in a fuel cell resulted in achieving a power output of >900 mW cm-2 while operating at 550 °C. Therefore, we have found that laterally combining di- and tri-valent doping could be textured to give a highly oxygen-deficient CeO2 structure with high ionic transport. Furthermore, various microscopic and spectroscopic analyses, such as HR-TEM, XPS, Raman, UV-visible, EIS, and density functional theory, were applied to investigate the change in structural properties and mechanism of the ionic transport of the synthesized La and Sr co-doped CeO2 electrolyte. This work provides some new insights for designing high-ionic-conductivity electrolytes from low-cost semiconductor oxides for energy storage and conversion devices.

2D MXenes Embedded Perovskite Hydrogels for Efficient and Stable Solar Evaporation.

Solar evaporation is a facile and promising technology to efficiently utilize renewable energy for freshwater production and seawater desalination. Here, the fabrication of self-regenerating hydrogel composed of 2D-MXenes nanosheets embedded in perovskite La 0.6Sr 0.4Co 0.2Fe 0.8O3- δ (LSCF)/polyvinyl alcohol hydrogels for efficient solar-driven evaporation and seawater desalination is reported. The mixed dimensional LSCF/Ti3C2 composite features a localized surface plasmonic resonance effect in the polymeric network of polyvinyl alcohol endows excellent evaporation rates (1.98 kg m-2 h-1) under 1 k Wm-2 or one sun solar irradiation ascribed by hydrophilicity and broadband solar absorption (96%). Furthermore, the long-term performance reveals smooth mass change (13.33 kg m-2) during 8 h under one sun. The composite hydrogel prompts the dilution of concentrated brines and redissolves it back to water (1.2 g NaCl/270 min) without impeding the evaporation rate without any salt-accumulation. The present research offers a substantial opportunity for solar-driven evaporation without any salt accumulation in real-life applications.

Enabling fast ionic transport in CeO2-La1-2xBaxBixFeO3 nanocomposite electrolyte for low temperature solid oxide fuel cell application.

Recent studies indicate that electrolyte ionic conductivity plays a pivotal role in reducing the operating temperature of solid oxide fuel cells (SOFCs). In this regard, nanocomposite electrolytes have drawn significant attention owing to their enhanced ionic conductivity and fast ionic transport. In this study, we fabricated CeO2-La1-2xBaxBixFeO3 nanocomposites and tested them as a high-performance electrolyte for low-temperature solid oxide fuel cells (LT-SOFCs). The prepared samples were characterized by their phase structure, surface, and interface property via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), followed by being applied in SOFCs to examine their electrochemical performance. In the fuel cells, it was found that the optimal composition 90CeO2-10La1-2xBaxBixFeO3 electrolyte-based SOFC delivered a peak power density of 834 mW cm-2 along with an open circuit voltage (OCV) of 1.04 V at 550 °C. A comparative study revealed that the nanocomposite electrolyte exhibited a total conductivity of 0.11 S cm-1 at 550 °C. Moreover, the rectification curve manifested the formation of the Schottky junction, suppressing the electronic conduction. This study conclusively shows that the addition of La1-2xBaxBixFeO3 (LBBF) into ceria electrolyte is a viable approach for constructing high-performance electrolytes for LT-SOFCs.

Strontium-Cobaltite-Based Perovskite (SrCoO3) for Solar-Driven Interfacial Evaporation Systems for Clean Water Generation.

Solar-driven evaporation technology is often used in areas with limited access to clean water, as it provides a low-cost and sustainable method of water purification. Avoiding salt accumulation is still a substantial challenge for continuous desalination. Here, an efficient solar-driven water harvester that consists of strontium-cobaltite-based perovskite (SrCoO3) anchored on nickel foam (SrCoO3@NF) is reported. Synced waterways and thermal insulation are provided by a superhydrophilic polyurethane substrate combined with a photothermal layer. The structural photothermal properties of SrCoO3 perovskite have been extensively investigated through state-of-the-art experimental investigations. Multiple incident rays are induced inside the diffuse surface, permitting wideband solar absorption (91%) and heat localization (42.01 °C @ 1 sun). Under 1 kW m-2 solar intensity, the integrated SrCoO3@NF solar evaporator has an outstanding evaporation rate (1.45 kg/m2 h) and solar-to-vapor conversion efficiency (86.45% excluding heat losses). In addition, long-term evaporation measurements demonstrate small variance under sea water, illustrating the system's working capacity for salt rejection (1.3 g NaCl/210 min), which is excellent for an efficient solar-driven evaporation application compared to other carbon-based solar evaporators. According to the findings of this research, this system offers significant potential for producing fresh water devoid of salt accumulation for use in industrial applications.

Rational Design of Trimetallic Sulfide Electrodes for Alkaline Water Electrolysis with Ampere-Level Current Density.

Electrochemical water splitting is considered an environmentally friendly approach to hydrogen generation. However, it is difficult to achieve high current density and stability. Herein, we design an amorphous/crystalline heterostructure electrode based on trimetallic sulfide over nickel mesh substrate (NiFeMoS/NM), which only needs low overpotentials of 352 mV, 249 mV, and 360 mV to achieve an anodic oxygen evolution reaction (OER) current density of 1 A cm-2 in 1 M KOH, strong alkaline electrolyte (7.6 M KOH), and alkaline-simulated seawater, respectively. More importantly, it also shows superior stability with negligible decay after continuous work for 120 h at 1 A cm-2 in the strong alkaline electrolyte. The excellent OER performance of the as-obtained electrode can be attributed to the strong electronic interactions between different metal atoms, abundant amorphous/crystalline hetero-interfaces, and 3D porous nickel mesh structure. Finally, we coupled NiFeMoS/NM as both the anode and cathode in the anion exchange membrane electrolyzer, which can achieve low cell voltage and high stability at ampere-level current density, demonstrating the great potential of practicability.

Recent Advances in the Synthesis of MXene Quantum Dots.

Quantum dots (QDs) with ultrahigh surface-to-volume ratio, abundant edge active sites, forceful quantum confinement and other remarkable physio-chemical properties, have garnered considerable research interest. MXene QDs, as an emerging member of them, have also attracted wide attention in the last six years, and shown great achievements in many fields. This critical review systematically summarizes the various methods for synthesizing MXene QDs. The characteristics and corresponding applications of various MXene QDs are also presented. The advantages and disadvantages of various synthetic methods, and the limitations of corresponding MXene QDs are compared and highlighted. Finally, the challenges and perspectives of synthesizing MXene QDs are proposed. We hope this review will enlighten researchers to the fabrication of more advancing and promising MXene-based QDs with proprietary properties in diverse applications.