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Two-dimensional (2D) pseudohexagonal ZnSe (h -ZnSe) nanosheet has been sythesized and demonstrated to be a stable, cut-price and high-efficiency photocatalyst under the irradiation of ultraviolet light. Herein, we use hybrid density functional theory to rationally design the charge-compensated codoped h -ZnSe sheets, which are simulated by substituting Sb for Se atom, and Sc or Y for Zn atom, for visible-light-driven photocatalytic water splitting to produce hydrogen. It is demonstrated that the Sc–Sb and Y–Sb codoped sheets are energetically favorable compared with Sc, Y, Sb-monodoped sheets because dopants have strong Coulombic interactions with other atoms, and moreover, have the effectively reduced bandgap, the larger absorption region of visible light, and appropriate band edges positions with respect to the water redox level. Meanwhile, compared to monodoped sheets, the codoped sheets do not introduce charge-imbalance defects or unoccupied impurity states which promote the electron-hole recombination. Furthermore, the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are easier driven by photogenerated carriers due to the largely reduced overpotentials and ample active sites on the codoped sheets. Thus, the Sc–Sb and Y–Sb codoped h -ZnSe sheets can be promising photocatalysts for visible-light-driven water decomposition to generate hydrogen. [Display omitted] • Sc-or Y-Sb passivated codoping can effectively reduce band gap of pseudohexagonal ZnSe sheet. • Codoped ZnSe sheets have suitable positions of band edges with respect to the water redox potentials. • Codoping can promote the visible light absorption of ZnSe sheet. • Codoping can reduce the overpotential of ZnSe sheet for OER and HER. • Sc-or Y-Sb codoped ZnSe sheets are promising visible-light-driven photocatalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel, environmental benign, boosted Lay-by-Layer assembly approach was provided. • Functional cotton displayed excellent flame retardancy via both gaseous and condensed phases. • The concept of π − π stacking to help improve durability for Lay-by-Lay coating was first to put forward here. Layer-by-Layer (LbL) assembly was attractive as a versatile tool to address the flammability of cotton, while the washing fastness of LbL coating stayed an issue. Aiming to tackle this issue, LbL layers consisted of phenylphosphonic acid (PHA) and 3-aminopropyltriethoxysilane (APTES) was deposited on polydopamine (PDA)-coated cotton. The prepared cotton reached 31.4% of limiting oxygen index (LOI), and extinguished immediately after removing the ignitor. Peak of heat release rate (pHRR) attenuated around 36 % compared with pure cotton. A combined barrier and quenching mechanisms were proposed. Moreover, enhanced washing durability (24.1% of LOI) was achieved even after 50 detergent laundering cycles. A facile, boosted LbL approach with proposed π − π stacking interactions between PDA abundant aromatic structures and benzene ring in PHA from LbL layers, is first to put forward to construct durable efficient flame retardant (FR) cotton. This work attempted to enlighten more thoughts and design for durable FR cotton fabrics. [ABSTRACT FROM AUTHOR]

• Non-halogenated method to functional cotton fabrics was developed. • Functional fabrics displayed good flame retardancy via both gaseous and condensed phases. • Functional fabrics exhibited excellent hydrophobic property. The demand for multifunctional cotton fabrics possessing fire retardancy and hydrophobic self-cleaning property is soaring in recent years. In this work, non-halogen functional coatings by water-soluble phenylphosphinyl and amine-containing silanol (WPAS) were prepared through sol-gel method, in which functional cotton fabrics embraced with flame retardant (FR) and hydrophobic properties, simultaneously. The prepared WPAS coated functional fabrics reached as high as 30.4% for LOI value, and extinguished immediately after removing the ignitor in vertical fire test. Low-energy •PO free radicals released by WPAS which was detected by TG-MS and TG-FTIR, captured high energy radicals such as •H or •OH radicals in the gas-phase. The char residue study from SEM, FTIR, Raman and XPS results found that P/Si/N thermostable ceramic char layer and aromatic carbonaceous structures formed which could provide a good barrier effect, effectively hindering diffusion of oxygen and transferring of heat into the flame zone. Additionally, water contact angle of functional cotton increased to 145° compared with cotton. As a result, it displayed hydrophobic self-cleaning property towards a series of common liquids in daily life. This convenient, eco-friendly one-pot approach is promising, and feasible for large-scale production of functional cotton fabrics with both excellent FR and hydrophobic self-cleaning properties to end-use industrial applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Waste coffee grounds were catalytically carbonized into functional carbon materials and used as high-efficient adsorbent for organic dyes. Highlights • Biowaste coffee grounds were converted into functional carbon materials. • The carbon yield was as high as 47.6 wt% via direct catalysis by 20 wt% FeCl 3. • The synthesized carbon achieved high surface area and mesoporous structure. • The functional carbon was effective for the removal of different dyes. • The obtained carbon can be magnetically separated and reused multiple times. Abstract Functional carbon materials have been fabricated through simple and effective catalytic carbonization with waste coffee grounds (CGs) as carbon precursor and FeCl 3 as catalyst. The effect of FeCl 3 loading and carbonization temperature on carbon yield was investigated. The morphology and structure of as-synthesized carbons was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and nitrogen isothermal adsorption/desorption measurement, respectively. Furthermore, the carbon materials showed high efficiency for the removal of methylene blue (MB, 653.6 mg g−1), methyl orange (MO, 465.8 mg g−1) and rhodamine B (RB, 366.1 mg g−1). More importantly, the carbon was magnetic, so it can be easily separated by a magnet and reused multiple times. This work not only exploited a low–cost and large-scale preparation method to synthesize functional carbon materials from bioresources, but also provided an eco-friendly and effective adsorbent in water purification applications. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO 2 ) is an ideal electrode material for supercapacitors due to its low cost and large theoretical specific capacity. We reported the hydrothermal synthesis MnO 2 nanostructures with different morphologies through the variation of hydrothermal temperature and dwell time. It was found that cauliflower-like δ-MnO 2 particles are prepared at a lower temperature while the needle-like α-MnO 2 nanorods are formed at a higher temperature. The morphologies of MnO 2 were also affected by the hydrothermal dwell time. The needle-like α-MnO 2 nanorods have the higher specific surface (114 m 2  g −1 ) than that of the cauliflower-like δ-MnO 2 particles. Electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The hierarchical multidimensional MnO 2 architecture nanostructured surface with particles and nanorods, shows a maximum specific capacity (311.52 F g -1  at 0.3 A g −1 ). These results provided a generic guideline in developing different nanostructured electrode materials for electrochemical energy storage. [ABSTRACT FROM AUTHOR]