Borophene Embedded Cellulose Paper for Enhanced Photothermal Water Evaporation and Prompt Bacterial Killing

Chiral Induction in 2D Borophene Nanoplatelets through Stereoselective Boron-Sulfur Conjugation

Chirality is a structural metric that connects biological and abiological forms of matter. Although much progress has been made in understanding the chemistry and physics of chiral inorganic nanoparticles over the past decade, almost nothing is known about chiral two-dimensional (2D) borophene nanoplatelets and their influence on complex biological networks. Borophene's polymorphic nature, derived from the bonding configurations among boron atoms, distinguishes it from other 2D materials and allows for further customization of its material properties. In this study, we describe a synthetic methodology for producing chiral 2D borophene nanoplatelets applicable to a variety of structural polymorphs. Using this methodology, we demonstrate feasibility of top-down synthesis of chiral χ3 and β12 phases of borophene nanoplatelets via interaction with chiral amino acids. The chiral nanoplatelets were physicochemically characterized extensively by various techniques. Results indicated that the thiol presenting amino acids, i.e., cysteine, coordinates with borophene in a site-selective manner, depending on its handedness through boron-sulfur conjugation. The observation has been validated by circular dichroism, X-ray photoelectron spectroscopy, and 11B NMR studies. To understand how chiral nanoplatelets interact with biological systems, mammalian cell lines were exposed to them. Results showed that the achiral as well as the left- and right-handed biomimetic χ3 and β12 borophene nanoplatelets have distinct interaction with the cellular membrane, and their internalization pathway differs with their chirality. By engineering optical, physical, and chemical properties, these chiral 2D nanomaterials could be applied successfully to tuning complex biological events and find applications in photonics, sensing, catalysis, and biomedicine.

Well-designed lamellar reduced graphene oxide-based foam for high-performance solar-driven water purification

Although solar steam generation is promising for seawater desalination, it is less effective in purifying wastewater with both salt/heavy metal ions and organic contaminants. It is thus imperative to develop multifunctional integrated solar-driven water purification systems with high solar-thermal evaporation and photocatalytic degradation efficiencies. Herein, a lamellar reduced graphene oxide (L-RGO) foam with the vertical lamellar structure is fabricated by bidirectional-freezing, lyophilization, and slight chemical reduction for water purification. The unique vertical lamellar structure not only accelerates upward transport of water for facilitating water evaporation but also endows the L-RGO foam with superb high elasticity for tuning the interlayer distance and varying interactions between the oxygen-containing groups and water molecules to adjust water energy state. As a result, the L-RGO foam achieves a superb water evaporation rate of 2.40 kg m-2 h-1 along with an energy efficiency of 95.3 % under the compressive strain of 44.7 % under 1-sun irradiation. Equally importantly, the decoration of L-RGO foam with polypyrrole is capable of efficiently degrading organic pollutants while retaining high solar steam generation performances, exhibiting great potential in the comprehensive treatment of various water sources for relieving freshwater crisis.

A Solar Evaporator Based on Polypyrrole Coated 3D Carbon Nanotube Materials for Efficient Solar-Driven Vapor Generation

Highly porous light absorbers are fabricated based on polypyrrole (PPy)-coated carbon nanotube (CNT). Carbon nanotube sponge (CNTS) or carbon nanotube array (CNTA) with three-dimensional (3D) network structure is the framework of porous light absorbers. Both PPy@CNTS and PPy@CNTA composites exhibit excellent light absorption of the full solar spectrum. The CNTS and CNTA with porous structures have extremely large effective surface area for light absorption and for water evaporation that has great practical benefit to the solar-driven vapor generation. The PPy layer on CNT sidewalls significantly improves the hydrophilicity of porous CNTS and CNTA. The good wettability of water on CNT sidewalls makes water transport in porous CNT materials highly efficient. The PPy@CNTS and PPy@CNTA light absorbers achieve high water evaporation rates of 3.35 and 3.41 kg m-2 h-1 , respectively, under 1-sun radiation. The orientation of nano channels in CNTA-based light absorbers also plays an important role in the solar-driven vapor generation. The water transport and vapor escape are more efficient in CNTA-based light absorbers as compared to the CNTS-based light absorbers due to the relatively short path for the water transport and the vapor escape in CNTA-based light absorbers.

Unidirectional Nano-modulated Binding and Electron Scattering in Epitaxial Borophene

A complex interplay between the crystal structure and the electron behavior within borophene renders this material an intriguing 2D system, with many of its electronic properties still undiscovered. Experimental insight into those properties is additionally hampered by the limited capabilities of the established synthesis methods, which, in turn, inhibits the realization of potential borophene applications. In this multimethod study, photoemission spectroscopies and scanning probe techniques complemented by theoretical calculations have been used to investigate the electronic characteristics of a high-coverage, single-layer borophene on the Ir(111) substrate. Our results show that the binding of borophene to Ir(111) exhibits pronounced one-dimensional modulation and transforms borophene into a nanograting. The scattering of photoelectrons from this structural grating gives rise to the replication of the electronic bands. In addition, the binding modulation is reflected in the chemical reactivity of borophene and gives rise to its inhomogeneous aging effect. Such aging is easily reset by dissolving boron atoms in iridium at high temperature, followed by their reassembly into a fresh atomically thin borophene mesh. Besides proving electron-grating capabilities of the boron monolayer, our data provide comprehensive insight into the electronic properties of epitaxial borophene which is vital for further examination of other boron systems of reduced dimensionality.

Bacterial cellulose-based film with self-floating hierarchical porous structure for efficient solar-driven interfacial evaporation

Interface solar water evaporation is a mean of rapidly evaporating water using solar energy. However, it is still a challenge to obtain solar evaporators with simple assembly, durability and high photothermal performance. Here, we demonstrated an effective post foaming strategy for treating nitrogen-doped reduced graphene oxide/bacterial cellulose film (F-NRGO@BC) prepared by a simple in situ culture method. The composite film contains hierarchical porous structure and bubbles on the film, achieving an integrated self-floating interface evaporator with excellent light absorption (96.5 %) and high toughness (200.18 kJ m-3). Porous structure and low enthalpy of F-NRGO@BC make a high evaporation rate of 1.68 kg m-2 h-1 and a low thermal conductivity of 0.644 W m-1 K-1 to ensure effective energy efficiency and heat insulation. This design of controlling surface morphology and internal structure provides a novel way for large-scale preparation and high-performance evaporator.

Multifunctional carbon nitride nanoarchitectures for catalysis

Catalysis is at the heart of modern-day chemical and pharmaceutical industries, and there is an urgent demand to develop metal-free, high surface area, and efficient catalysts in a scalable, reproducible and economic manner. Amongst the ever-expanding two-dimensional materials family, carbon nitride (CN) has emerged as the most researched material for catalytic applications due to its unique molecular structure with tunable visible range band gap, surface defects, basic sites, and nitrogen functionalities. These properties also endow it with anchoring capability with a large number of catalytically active sites and provide opportunities for doping, hybridization, sensitization, etc. To make considerable progress in the use of CN as a highly effective catalyst for various applications, it is critical to have an in-depth understanding of its synthesis, structure and surface sites. The present review provides an overview of the recent advances in synthetic approaches of CN, its physicochemical properties, and band gap engineering, with a focus on its exclusive usage in a variety of catalytic reactions, including hydrogen evolution reactions, overall water splitting, water oxidation, CO2 reduction, nitrogen reduction reactions, pollutant degradation, and organocatalysis. While the structural design and band gap engineering of catalysts are elaborated, the surface chemistry is dealt with in detail to demonstrate efficient catalytic performances. Burning challenges in catalytic design and future outlook are elucidated.

Synergistic photothermal conversion and photocatalysis in 2D/2D MXene/Bi2S3 hybrids for efficient solar-driven water purification

Plasmonic hybrids are regarded as promising candidates for water purification due to their structure-dependent photocatalysis and photothermal performance. It remains a challenge to develop materials that possess these two characteristics for efficient water purification. Herein, plasmonic Ti3C2Tx/Bi2S3 two-dimensional (2D)/2D hybrids were prepared for efficient solar-driven water purification via the combination of photothermal conversion and photocatalysis. Benefitting from broad light absorption, large 2D/2D interfaces, and efficient charge transfer, the binary hybrids showed high-efficiency photothermal conversion and photothermal-assisted photocatalytic activity. By depositing these 2D/2D hybrids on a hydrophilic and porous cotton piece, the Ti3C2Tx/Bi2S3 membrane displayed a high water evaporation rate and solar-to-vapor efficiency under one-sun irradiation. The solar-driven evaporation of seawater, heavy metal ion solution, and dye solution jointly indicated that the plasmonic membrane shows great potential for drinkable water generation and industrial wastewater treatment. Most importantly, the synergistic effect of photothermal evaporation and photocatalysis of the Ti3C2Tx/Bi2S3 membrane on water purification was demonstrated. The polluted water can not only be treated by evaporation, but also be degraded via photocatalysis under solar light irradiation. This work provides new insight into designing functional materials for water purification based on the combination of photothermal conversion and photocatalysis.

Recent Advances in Carbon-Based Electrodes for Energy Storage and Conversion

Carbon-based nanomaterials, including graphene, fullerenes, and carbon nanotubes, are attracting significant attention as promising materials for next-generation energy storage and conversion applications. They possess unique physicochemical properties, such as structural stability and flexibility, high porosity, and tunable physicochemical features, which render them well suited in these hot research fields. Technological advances at atomic and electronic levels are crucial for developing more efficient and durable devices. This comprehensive review provides a state-of-the-art overview of these advanced carbon-based nanomaterials for various energy storage and conversion applications, focusing on supercapacitors, lithium as well as sodium-ion batteries, and hydrogen evolution reactions. Particular emphasis is placed on the strategies employed to enhance performance through nonmetallic elemental doping of N, B, S, and P in either individual doping or codoping, as well as structural modifications such as the creation of defect sites, edge functionalization, and inter-layer distance manipulation, aiming to provide the general guidelines for designing these devices by the above approaches to achieve optimal performance. Furthermore, this review delves into the challenges and future prospects for the advancement of carbon-based electrodes in energy storage and conversion.

Stimuli-Responsive Silica Silanol Conjugates: Strategic Nanoarchitectonics in Targeted Drug Delivery

The design of novel drug delivery systems is exceptionally critical in disease treatments. Among the existing drug delivery systems, mesoporous silica nanoparticles (MSNs) have shown profuse promise owing to their structural stability, tunable morphologies/sizes, and ability to load different payload chemistry. Significantly, the presence of surface silanol groups enables functionalization with relevant drugs, imaging, and targeting agents, promoting their utility and popularity among researchers. Stimuli-responsive silanol conjugates have been developed as a novel, more effective way to conjugate, deliver, and release therapeutic drugs on demand and precisely to the selected location. Therefore, it is urgent to summarize the current understanding and the surface silanols' role in making MSN a versatile drug delivery platform. This review provides an analytical understanding of the surface silanols, chemistry, identification methods, and their property-performance correlation. The chemistry involved in converting surface silanols to a stimuli-responsive silica delivery system by endogenous/exogenous stimuli, including pH, redox potential, temperature, and hypoxia, is discussed in depth. Different chemistries for converting surface silanols to stimuli-responsive bonds are discussed in the context of drug delivery. The critical discussion is culminated by outlining the challenges in identifying silanols' role and overcoming the limitations in synthesizing stimuli-responsive mesoporous silica-based drug delivery systems.