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Two-dimensional (2D) 1H molybdenum disulfide (1H-MoS2) is hard to be directly used in energy storage devices due to its inert basal plane and unfavorable 2D stacking. This work demonstrated how the basal plane of 1H MoS2 nanocrystals (NCs) can be activated to offer doubled specific capacitance by simple surface S depletions. Building on the expanded graphene with three-dimensional (3D) structures, as-prepared NCs were chemically grafted on the graphene surface to deliver stable energy storage and high capacitance, which overcame above challenges of 1H-MoS2. Aside from the mostly focused metastable phase, this work confirmed that the stable 1H Mo–S material is also promising in energy storage applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) monolayers are promising in electrochemical energy storages (EES), while their performance is still far below than that can be exploited. Understanding 2D monolayers, particularly thin nanocrystals (NCs) with and without surface modifications in EES would be interesting. This work demonstrates how monolayered molybdenum sulfide (Mo–S) NCs with S vacancies perform as a promising anode material to improve many aspects of lithium-ion batteries (LIBs), by utilizing their metallicity, multi-layer adsorption, minimized self-discharge and fast 2D capacitive processes. By way of examples, we demonstrate an increasing trend of the energy capacity and improved lithium diffusion kinetics associating with the S vacancy and phase change, a discharge capacity of 1409 mAh g−1 at 0.1 A g−1, and even reach the capacitive dominated (>814.7 mAh g−1) capacity at 1 A g−1. It demonstrates that the surface modified Mo–S NCs can be well used in LIBs. There may be also considerable opportunities of similar 2D materials in LIBs and beyond (e.g. supercapacitor) which can fully exploit the fast 2D capacitive process and high surface capacity. Image 1 • Basic Li+ storage behaviors of Mo–S NCs with controlled S-vacancies are explored. • Rich surface chemistry of S-depleted Mo–S NCs is beneficial to lithium diffusion kinetics. • Metallicity, multi-layer adsorption and fast 2D capacitive processes facilitate capacity improvements. [ABSTRACT FROM AUTHOR]

[Display omitted] The treatment of wastewater containing hypophosphite [P(I)] and phosphite [P(III)] is challenged by limitations of traditional Fenton oxidation such as low efficiency, secondary pollution and high costs. This study introduced a facile solvent-thermal method to synthesize Cu-Co 3 O 4 nanoparticles uniformly loaded on graphene (Cu-Co 3 O 4 /U-rGO) through the reduction and coordination effects of urushiol (U). As prepared Cu-Co 3 O 4 /U-rGO exhibited excellent activity in activating peroxymonosulfate (PMS) for the oxidation of P(I)/P(III) to phosphate [P(V)] (0.229 min−1), along with high stability and reusability (91.5 % after 6 cycles), low metal leaching rate (Co: 0.2 mg/L, Cu: 0.05 mg/L), insensitivity to common anions in water and a wide pH range (3–11). The activation mechanism involved the synergistic effects from both urushiol and graphene, which promoted redox of Cu+/Cu2+ and Co2+/Co3+ and induced abundant oxygen vacancies for PMS activation to produce singlet oxygen. Furthermore, the Cu-Co 3 O 4 /U-rGO/PMS was also excellent in the oxidative removal of organic phosphorus. This study is expected to advance strategies for the treatment of P(I)/P(III)-rich wastewater and provide new insights for the development of low-cost, highly efficient heterogeneous catalysts with abundant oxygen vacancies. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) porous molybdenum disulfide/nitrogen-doped reduced graphene oxide (MoS 2 /N-rGO) hydrogels were fabricated through a facile and controllable one-pot hydrothermal method. The nanosized MoS 2 ultrathin nanosheets were uniformly and vertically dispersed on the rGO framework after nitrogen incorporation. The incorporated nitrogen in rGO played a key role for nano-scaling of MoS 2 due to the protonation at pyridinic N-doping sites on carbon surface. The vertically aligned edge of nanosized MoS 2 sheets, nitrogen incorporation of rGO and 3D network structure made the MoS 2 /N-rGO highly efficient for hydrogen evolution reaction, with improved double-layer capacitance and turnover frequency, small onset overpotential of 119 mV, low Tafel slope of 36 mV·decade −1 and superior long-time catalytic stability. [ABSTRACT FROM AUTHOR]

A robust 3D graphene-based Fenton-like catalyst with hierarchical porous structure was prepared by solvothermal combined with mild post-heating. It exhibited rapid degradation (50.3% in 10 s, 97.3% in 10 mins) and reusability (86.8% after 7 cycles) of tetracycline (TC) in a wide pH range (3–11) and various water samples. Such excellent performance was attributed to the formation of a stable and compact 3D porous conductive network, which promotes the electron transfer between Fe species and H 2 O 2 , the activation of H 2 O 2 to generate OH and the reaction between OH and TC. [Display omitted] • Robust Fe 3 O 4 /3D graphene with hierarchical porous structure was prepared by solvothermal combined with post-heating. • The functionalization of urushiol on 3D graphene led to the growth of dense Fe 3 O 4 nanoparticles. • Post-heating treatment enhanced the mechanical properties and conductivity of Fe 3 O 4 /3D graphene. • OH was the dominant reactive radical on the degradation of tetracycline. • Fast electron transfer from catalyst to H 2 O 2 resulted in OH generation. The Fenton like catalyst Fe 3 O 4 is still limited in wastewater treatment due to its narrow pH range, metal shedding and low catalytic efficiency. Here, a robust urushiol mediated Fe 3 O 4 /three-dimensional (3D) graphene was proposed to tackle these challenges. Fe 3 O 4 /3D-PU-G (H) was established by loading dense Fe 3 O 4 nanoparticles onto urushiol functionalized 3D graphene via simple solvothermal and mild post-heating. It exhibited rapid degradation (50.3% in 10 s, 97.3% in 10 mins) and reusability (86.8% after 7 cycles) of tetracycline (TC) in a wide pH range (3–11) and various waste water samples. Such excellent performance was attributed to the formation of a stable and compact 3D porous conductive network, which promotes the electron transfer between Fe species and H 2 O 2 , the activation of H 2 O 2 to generate OH and the reaction between OH and TC. This work provides a feasible approach for the preparation of efficient heterogeneous catalytic materials. [ABSTRACT FROM AUTHOR]

Cleaning up water contaminants discharged from various industries requires novel materials and approaches. Much effort has been focused on developing such materials including the three-dimensional graphene (3D-G) because of its outstanding physical features. Unfortunately, the relative poor mechanical properties of the most pristine 3D-G limit the recyclability, making them unsuitable for efficient and economic uses. Here, we show a simple and green approach to fabricating 3D-G based composites with various performances largely improved from pure 3D-G. We introduced urushiol monomers which reacted with and polymerized on graphene oxide (GO) sheets, to form 3D-G connected by polymer skeleton. Comparing with traditional 3D-G, the prepared 3D polyurushiol/graphene (3D-PU-G) composite showed remarkable improvement on hydrophobicity, adsorption capacity, mechanical strength and recyclability, which are well suited for water cleanup. By way of example, we have demonstrated the stable and high strength over 20 kPa of 3D-PU-G. The prepared 3D-PU-G also showed efficiently improved adsorption capacity (1.62–1.97 times) from 3D-G for cleaning up various organic solvents and oils from water. Most importantly, our prepared 3D-PU-G composite exhibited highly stable strength and adsorption capacity ever after running for over 100 cycles, whilst those of 3D-G are really poor, i.e. cannot run the 4th cycle to adsorb oil. The study here shows not only the preparation of a 3D-G based composite for water cleanup, but also a general concept to modify graphene for various purposes ( e.g. super hydrophobicity for anti-corrosion). [ABSTRACT FROM AUTHOR]

Dense CuO x -CoO y nano-heterostructures were uniformly assembled on the surface of graphene by one-pot method under mild reaction conditions through the induced assembly of PVP and reduction of NaBH 4. Owing to the combination (e.g. suitable surface electronic structure and good catalytic kinetics) of graphene and CuO x -CoO y heterostructures, this material exhibited excellent selectivity, catalytic activity and cycle stability in the oxidation of HMF to value-added chemical FDCA with NaClO as oxidant at 30 °C. [Display omitted] • Dense CuO x -CoO y heterostructures assembled on graphene surface by one-pot method. • PVP reduced the size of CuO x -CoO y and enhanced metal loading on graphene. • Heterostructure regulated electronic states and promoted charge transfer process. • CuO x -CoO y -PVP/G shows high catalytic performance on the conversion of HMF to FDCA. Dense CuO x -CoO y nano-heterostructures were uniformly assembled on the surface of graphene via surfactant induced assembly and hydrolysis with the presence of PVP and NaBH 4. As-prepared CuO x -CoO y -PVP/G composite exhibited excellent performance for selective oxidation of 5-HMF to FDCA in aqueous solution with NaClO as oxidant at 30 °C, which is comparable to noble metal catalysts. The outstanding performance can be attributed to fascinating synergetic contributions from the CuO x -CoO y heterostructure on graphene substrate, giving improved interfacial contact, increased active sites and accelerated electron transfer process to promote the catalytic reaction. This work provides a high-performing catalyst for oxidation of 5-HMF to FDCA, as well as an ideal design of metal-oxide heterostructures/graphene composite catalysts for more broad applications. [ABSTRACT FROM AUTHOR]