Anisotropic Black Phosphorene Structural Modulation for Thermal Storage and Solar-Thermal Conversion.

Exploiting novel strategies for simultaneously harvesting ubiquitous, renewable, and easily accessible solar energy based on the photothermal effect, and efficiently storing the acquired thermal energy plays a vital role in revolutionizing the current fossil fuel-dominating energy structure. Developing black phosphorene-based phase-change composites with optimized photothermal conversion efficiencyand high latent heat is the most promising way to achieve efficient solar energy harvesting and rapid thermal energy storage. However, exfoliating high-quality black phosphorene nanosheets  remains challenging, Furthermore, an efficient strategy that can construct the aligned black phosphorene frameworks to maximize thermal conductivity enhancement is still lacking. Herein, high-quality black phosphorene nanosheets are prepared by an optimized exfoliating strategy. Meanwhile, by regulating the temperature gradient during freeze-casting, the framework consisting of shipshape aligned black phosphorene at long-range is successfully fabricated, improving the thermal conductivity of the poly(ethylene glycol) matrix up to 1.81 W m-1  K-1 at 20 vol% black phosphorene loading. The framework also endows the composite with excellent phase-change material encapsulation capacity and  high latent heat of 103.91 J g-1 . It is envisioned that the work advances the paradigm of contrasting frameworks with nanosheets toward controllable structure thermal enhancement of the composites.

A mucus-inspired solvent-free carbon dot-based nanofluid triggers significant tribological synergy for sulfonated h-BN reinforced epoxy composites.

Nano-filler reinforced polymer-based composites have attracted extensive attention in tribology; however, to date, it is still challenging to construct a favorable lubricating system with excellent compatibility, lubricity and durability using nano-filler reinforced polymer-based composites. Herein, sulfonated boron nitride nano-sheets (h-BN@PSDA) are prepared and used as nano-fillers for epoxy resins (EPs), to improve friction and wear along with thermal conductivity. Furthermore, inspired by the lubricating principle and structure of snail mucus, a solvent-free carbon dot-based nanofluid (F-CDs) is fabricated and used for the first time as the lubricant for h-BN@PSDA/EPs. Both poly (4-styrene sulfonate) and polyether amine grafted on the surface of F-CDs contribute to branched structures and multiple interfacial absorption effects. Extraordinarily low friction and wear are detected after long-term sliding. The average coefficient of friction and wear rate of h-BN@PSDA/EPs composites are reduced by 95.25% and 99.42% respectively, in the presence of the F-CD nanofluid, compared to that of EPs. Besides, the added h-BN nano-sheets increase the thermal conductivity (TC) of EPs from 0.178 to 0.194 W (m-1 K-1). The distinguished lubrication performances are likely due to the formation of a hybrid nanostructure of 0D F-CDs and 2D h-BN@PSDA together with the "rolling-sliding" and "self-mending" effects of added F-CDs.

Outstanding Bio-Tribological Performance Induced by the Synergistic Effect of 2D Diamond Nanosheet Coating and Silk Fibroin.

Due to their excellent biocompatibility, outstanding mechanical properties, high strength-to-weight ratio, and good corrosion resistance, titanium (Ti) alloys are extensively used as implant materials in artificial joints. However, Ti alloys suffer from poor wear resistance, resulting in a considerably short lifetime. In this study, we demonstrate that the chemical self-assembly of novel two-dimensional (2D) diamond nanosheet coatings on Ti alloys combined with natural silk fibroin used as a novel lubricating fluid synergistically results in excellent friction and wear performance. Linear-reciprocating sliding tests verify that the coefficient of friction and the wear rate of the diamond nanosheet coating under silk fibroin lubrication are reduced by 54 and 98%, respectively, compared to those of the uncoated Ti alloy under water lubrication. The lubricating mechanism of the newly designed system was revealed by a detailed analysis of the involved microstructural and chemical changes. The outstanding tribological behavior was attributed to the establishment of artificial joint lubrication induced by the cross binding between the diamond nanosheets and silk fibroin. Additionally, excellent biocompatibility of the lubricating system was verified by cell viability, which altogether paves the way for the application of diamond coatings in artificial Ti joint implants.

Enhanced thermal transportation across an electrostatic self-assembly of black phosphorene and boron nitride nanosheets in flexible composite films.

For effective heat dissipation in portable electronics, there is a great demand for lightweight and flexible films with superior thermal transport properties. Despite extensive efforts, enhancing the intrinsic low thermal conductivity of polymers while simultaneously maintaining their flexibility is difficult to achieve due to the dilemma of quarrying appropriate filler loading. Herein, a cellulose nanofiber-based film with high in-plane thermal conductivity up to 72.53 W m-1 K-1 was obtained by harnessing the advantage of functionalized boron nitride nanosheets (f-BNNS) and black phosphorene (BP) via the vacuum filtration process. Besides, our unique design based on the electrostatic coupling of black phosphorene and functionalized boron nitride nanosheets significantly reduced the interfacial thermal resistance of the composite films. This work offers new insights into establishing a facile, yet efficient approach to preparing high thermal conductive heat spreaders.

Two-Stage Super-Efficiency Slacks-Based Model to Assess China's Ecological Wellbeing.

As industrialization and urbanization in China have significantly increased ecological problems such as environmental pollution and resource waste, it has become important to be able to comprehensively assess ecological wellbeing performance (EWP) when seeking high-quality human wellbeing and economic growth within specific ecological limits. Therefore, to explore the EWP spatial and temporal distribution characteristics, this paper established an evaluation index system that considers ecological economic efficiency and economic welfare efficiency from input and output perspectives. The EWPs in 30 Chinese provinces (autonomous regions, municipalities) from 2006 to 2017 were then measured using a two-stage super-efficiency slacks-based model (Super-SBM) and data envelopment analysis (DEA) window analysis method. It was found that: (1) the average EWP value in the Chinese provinces was relatively low at 0.698, with the highest EWP in Beijing, Hainan, and Shanghai and the lowest in Xinjiang, Ningxia, and Qinghai; (2) the average provincial EWP fluctuated from 2006 to 2017 with a "decline-rise-decline-rise" feature; (3) China's EWP value was spatially supported by the quadrangular "Beijing-Shanghai-Hainan-Sichuan" pole and continued to radiate to areas along these lines. These research findings provide theoretical insights and practical implications for regional ecological protection and human welfare improvements in China.