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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).

The coke-oven-gas-to-methanol (CGTM) process is one of the most important coal-to-chemical processes. However, it suffers from ineffective hydrogen utilization, limiting both its capacity and energy efficiency. In addition, currently, there is a large amount of low-quality pulverized coke that cannot be used for value-added applications. In this paper, two pulverized coke-assisted CGTM processes (PC-CGTM1&2) are proposed. In these processes, coke-oven gas is either partially oxidized or steam reformed to generate a hydrogen-rich syngas, and simultaneously gas produced by the gasification of pulverized coke is used to adjust the ratio of hydrogen and carbon to about 2, ideal for methanol synthesis. The results show that the optimized mass ratios of PC/COG are 0.27 and 0.51 for the PC-CGTM1&2, respectively. Their exergy efficiencies are increased to 71.3% and 75.9% from 58.6% in the CGTM process. Their methanol productivities are also increased to 0.63 and 0.75 from 0.43 Mt/y. The total product costs of the PC-CGTM1&2 are 21 and 43 US$/t lower than that of the CGTM (282 US$/t). The internal rates of return for these new processes are 19.7% and 25.7%, whereas it is only 13.5% for the CGTM, demonstrating the ability of the new processes to resist inflation and market risk.

Efficient utilization of a large quantity of coke-oven gas (COG) to produce methanol and further olefins is an important technical path toward coal-to-chemicals. The current COG-to-olefins process (CGTO) suffers from inefficient utilization of hydrogen resource in the COG, limited olefins productivity, lower energy efficiency, and ultimately uncompetitive in product cost. Its major technical issues are the insufficient carbon supply and energy intensification. This study provided a novel technical path toward olefins production fueled by syngas from efficient coupling of COG reforming with pulverized coke chemical looping combustion (PC CLC ). The CO 2 generated by the PC CLC was used as carbon source to effectively adjust hydrogen-to-carbon ratio of syngas to 2.0, ideally adapting to methanol production first and further olefins. The coupling and integration in material streams and energy utilization were considered in the new process. Modelling and integration results supported the competitiveness of this novel process, revealing that its hydrogen efficiency and exergy efficiency can be increased to 43% and 60%, comparing to only 29% and 52% in the CGTO. The olefins capacity was also increased from 0.6 Mt/y in the CGTO to 0.9 Mt/y by an additional consumption of economic pulverized coke 0.43 Mt/y. Although total capital investment of the new process was 21% higher than the CGTO, the unit capital investment and product cost were 19% and 6% lower because of its larger olefins capacity.

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.