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In this study, a hydrothermal-prepared TiO2-RG nanocomposites series exhibited excellent photocatalytic activities, of which the results can be largely influenced by a Ti O C interfacial chemical bond between TiO2 nanoparticles and RG nanosheets. A stirring TiO2-RG sample was prepared as contrast analysis using the same wet process except for heating. The characteristics of the composites were tested by X-ray diffraction (XRD), Raman, FT-IR, Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis. The photocatalytic properties were verified by UV–vis diffuse reflectance spectra (DRS) testing as well as degrading Rhodamine B (RhB). Our research results show that the better Ti O C interfacial chemical bond was formed, the narrower band gap of the nanocomposite was then obtained. The best hydrothermal synthesizing temperature was found out as 120 °C. The TiO2-RG nanocomposite, as inexpensive, nontoxic and highly photo-catalytically active, may let it have a potential use in various photocatalytic applications.

The design and fabrication of advanced electrode materials for supercapacitor have been extensively explored recently. The spinel transition metal oxides have drawn considerable attentions because of their high theoretical capacity to store electrical charge. This work introduced a general hydrothermal assisted co-precipitation approach to fabricate five kinds of spinel MCo2O4 (M = Co, Mn, Fe, Mg and Zn) submicron prisms on nickel foams. Among these spinel MCo2O4 electrodes, the MgCo2O4 exhibited the highest specific capacity of 613.5 C g−1 (0.883 C cm−2) at a current density of 2 mA cm−2. All the specific capacities of bimetallic oxides were higher than single metal oxide Co3O4, indicating the enhanced electrochemical performance of bimetallic oxides. The correlations between peak currents and the square root of the scan rates of all prepared electrode materials showed OH− diffusion-controlled characteristic in their redox reactions. Furthermore, an assembled MgCo2O4//AC hybrid supercapacitor (HSC) achieved a specific capacity and a specific energy of 182.8 C g−1 at 0.5 A g−1 and 39.7 W h kg−1, respectively. More impressively, this MgCo2O4//AC HSC showed a subsequent increase about 21.1% in specific capacity after 5000 cycles, suggesting its promising characteristics for the next generation energy storage device.

The coke-oven gas (COG)-to-olefins (CGTO) process is an important technical path of coal chemical industry. However, it is far more effective and friendly in terms of energy efficiency and environment impact. A new scheme of pulverized coke (PC) chemical looping combustion (CLC)-assisted COG-to-olefins and ammonia (PCCLC-CGTOA) is proposed in this paper. The intensive energy and material couplings in the new process are realized by applying an energy-efficient and environmental-friendly CLC technology to the current CGTO. The PCCLC-derived CO2 is an effective carbon source to adjust ideal composition of syngas toward olefins production, while the PCCLC-derived N2 with the excessive H2 in COG is used for producing ammonia. The process configuration is flexibly adapted to market demand of olefins and ammonia in terms of economic optimization. Process modelling helps its process integration and intensification, and confirms its competitiveness and feasibility. The proposed PCCLC-CGTOA acclaims 58% of hydrogen utilization and 65% of exergy efficiency, contrasting to only 29% and 52% in the CGTO. There is a 25% increase of olefins production with additional 0.4 Mt/y ammonia output at the cost of economic PC. A higher internal rate of return is also expected (18.5% for the PCCLC-CGTOA versus 12.9% for the CGTO).

A new type of hierarchically mesoporous cobalt ferrite oxide nanosheets, CoFe2O4 nanosheets, has been successfully fabricated via a simple hydrothermal method on the Ni foam followed by a post-annealing treatment. This CoFe2O4 nanosheets was employed as a supercapacitor electrode and exhibited an excellent capacitance of 503 F g−1 at a current density of 2 A g−1. When the current density increased to 20 A g−1, the capacitance of CoFe2O4 nanosheets can maintain 78.5% (395 F g−1) of the initial value, indicating the remarkable rate capability of the as-prepared CoFe2O4 nanosheets. An aqueous asymmetric supercapacitor (ASC) based on CoFe2O4 nanosheets as a positive electrode and the activated carbon (AC) as a negative electrode was assembled for the first time. The as-fabricated ASC delivered a specific capacitance of 73.12 F g−1 at a current density of 1.2 A g−1 in a voltage window of 1.5 V. The CoFe2O4//AC ASC could achieve a high energy density of 22.85 W h kg−1 and good long-term cycling stability (98% retention after 5000 cycles). These results demonstrated that CoFe2O4 nanosheets could be one of the promising electrode material for supercapacitors applications.

In this study, a hydrothermal method was successfully used to prepare a reduced graphene oxide (RG)–titanium dioxide (TiO2) hybrid in 10–20 nm, starting from commercial TiO2 P25 nanoparticles and liquid-exfoliated graphene oxide (GO). Compared to TiO2, an obvious red shift of light absorption (from 3.1 to 2.6 eV) of the as-prepared RG–TiO2 was observed by UV–Vis analysis, and an enhanced photocatalytic degradation of the Rhodamine B (Rh. B) was also observed under Xe lamp exposure test by using the as-prepared RG–TiO2. Multiple characterizations of this RG–TiO2 nanocomposite confirmed that its photocatalytic enhancement could be ascribed to two approaches. Firstly, RG extended the mean free path and photogenerated electrons’ lifetime of TiO2, which minimized electron–hole pairs’ recombination. Secondly, RG expanded the light absorption spectrum of TiO2 from UV range to UV and visible light range. The explication of these improvements was concluded as the energy gap changing and a likelihood of up-conversion photoluminescence mechanism (UCPL). Due to the low-cost, nonpoisonous and excellent photocatalytic properties of RG–TiO2, this material can be applied well in sewage treatment and other related fields.

We developed a simple and controlled method to synthesize FeCo2O4@MnO2 core–sheath nanoarchitecture (CSN) grown on Ni foam. Ultrathin FeCo2O4 nanoflakes with an average thickness of 10 nm served as the scaffold to deposit the MnO2 nanosheets. The MnO2 nanosheets were able to vertically grow on FeCo2O4 nanoflakes to form a sheath via a hydrothermal reaction. The nanocomposites' thickness could be tailored from 80 nm–550 nm by changing the reaction times. Electrochemical measurements demonstrated that FeCo2O4@MnO2 CSN with an optimal thickness of about 400 nm achieved an areal capacitance of 3.077 F cm−2 at 2 mA cm−2, which is much higher than individual FeCo2O4 nanoflakes (0.295 F cm−2) and MnO2 nanosheets (1.065 F cm−2). An aqueous asymmetric supercapacitor (ASC) was assembled using FeCo2O4@MnO2 CSN as its positive electrode and activated carbon (AC) as its negative electrode. The FeCo2O4@MnO2⫽AC ASC exhibited a capacitance of 0.538 F cm−2 at 5 mA cm−2 with a potential window of 1.65 V, and an excellent cycling stability (99.1% retention even after 5000 cycles). Furthermore, the maximum energy density and power density of FeCo2O4@MnO2⫽AC ASC was 0.203 mWh cm−2 at 3.44 mW cm−2 and 28.6 mW cm−2 at 0.061 mWh cm−2, respectively.