Renaissance of elemental phosphorus materials: properties, synthesis, and applications in sustainable energy and environment.

The polymorphism of phosphorus-based materials has garnered much research interest, and the variable chemical bonding structures give rise to a variety of micro and nanostructures. Among the different types of materials containing phosphorus, elemental phosphorus materials (EPMs) constitute the foundation for the synthesis of related compounds. EPMs are experiencing a renaissance in the post-graphene era, thanks to recent advancements in the scaling-down of black phosphorus, amorphous red phosphorus, violet phosphorus, and fibrous phosphorus and consequently, diverse classes of low-dimensional sheets, ribbons, and dots of EPMs with intriguing properties have been produced. The nanostructured EPMs featuring tunable bandgaps, moderate carrier mobility, and excellent optical absorption have shown great potential in energy conversion, energy storage, and environmental remediation. It is thus important to have a good understanding of the differences and interrelationships among diverse EPMs, their intrinsic physical and chemical properties, the synthesis of specific structures, and the selection of suitable nanostructures of EPMs for particular applications. In this comprehensive review, we aim to provide an in-depth analysis and discussion of the fundamental physicochemical properties, synthesis, and applications of EPMs in the areas of energy conversion, energy storage, and environmental remediation. Our evaluations are based on recent literature on well-established phosphorus allotropes and theoretical predictions of new EPMs. The objective of this review is to enhance our comprehension of the characteristics of EPMs, keep abreast of recent advances, and provide guidance for future research of EPMs in the fields of chemistry and materials science.

Black Phosphorus/Carbon Nanoframes for Efficient Flexible All-Solid-State Supercapacitor.

A flexible all-solid-state supercapacitor with fast charging speed and high power density is a promising high-performance energy storage and sensor device in photovoltaic systems. Two-dimensional black phosphorus (BP) is a prospective electrode nanomaterial, but it struggles to fully exert its properties limited by its self-stacking. Herein, by embedding carbon nanoparticles into the interlayer of BP microplates, the designed BP/carbon nanoframe (BP/C NF) forms a certain nano-gap on the substrate for promoting the orderly transport of charges. The corresponding supercapacitor BP/C SC has a capacity of 372 F g-1, which is higher than that constructed from BP microplates (32.6 F g-1). Moreover, the BP/C SC exhibits good stability with a ca. 90% of capacitance retentions after 10,000 repeated bending and long-term cycles. Thus, the proposed strategy of using BP/carbon nanoframes is feasible to develop exceptional flexible energy devices, and it can guide the design of relevant two-dimensional nanocomposites.

Size-dependent flame retardancy of black phosphorus nanosheets.

Two-dimensional black phosphorus (BP) nanosheets are potential flame-retardant nano-additives. Herein, the effects of the size of BP nanosheets embedded in epoxy resin (EP) on flame retardancy are studied. BP nanosheets with four different sizes are synthesized from bulk BP by different exfoliation methods including solid ball milling, liquid ball milling, ultrasonic liquid exfoliation, and electrochemical exfoliation (samples are designated as sb-BP, lb-BP, us-BP, and ec-BP, respectively). lb-BP exhibits the best dispersion in the EP matrix, and the lb-BP/EP composite shows the best flame-retardancy properties among the four BP/EP composites. Compared to bare EP, lb-BP/EP shows obvious improvements including the reduction in the heat release peak rate by 34.4%, total heat release by 27.0%, peak of smoke production rate by 69.2%, and total production of carbon monoxide by 50.8%. The mechanistic study reveals that lb-BP serves as a barrier and carbonization catalyst to delay combustion. These results confirm the size dependence of flame-retardancy properties of BP nanosheets and the new knowledge provides insights into the size dependent effects of other two-dimensional materials.

Copper(II)-ß-cyclodextrin and CuO functionalized graphene oxide composite for fast removal of thiophenic sulfides with high efficiency.

A novel copper(II)-ß-cyclodextrin and CuO functionalized graphene oxide composite (CD-CuO/NH2-GO) was successfully synthesized by reacting mono-6-O-toluenesulfonyl-copper(II)-ß-cyclodextrin with amino and CuO functionalized graphene oxide. The characterization results showed that the CD-CuO/NH2-GO was well-characterized and has a BET surface area of 746.5 m2 g-1 and good thermal stability, and CD and CuO were uniformly dispersed. The unique structure of CD-CuO/NH2-GO is conducive to the synergistic effect of the different components, especially for the inclusion ability of CD. Benefiting from that, CD-CuO/NH2-GO could quickly and efficiently remove the thiophenic sulfides, which are difficult to be economically removed by hydrodesulfurization. The removal efficiency for the three sulfides was in the order of benzothiophene > dibenzothiophene > thiophene. The desulfurization process of benzothiophene has the fastest desulfurization rate (0.121 g mg-1 min-1) and maximum sulfur capacity (12.75 mg S g-1). The different molecular inclusion ability of CD for the thiophenic sulfides demonstrates the difference in the desulfurization of CD-CuO/NH2-GO. The work highlights the synthesis and the potential application in fuel desulfurization of supramolecular GO composite nanomaterials.