Nickel cobaltite composite electrodes were fabricated by a fast, scalable, and cost-effective electrophoretic deposition for supercapacitor applications. NiCo 2 O 4 /PANI/rGO composite electrode went through heat treatment under nitrogen to carbonize PANI after electrophoretic deposition. NiCo 2 O 4 platelets, distributed on carbonized polyaniline−rGO network, were active in charge storage with high capacitance, excellent rate capability (1235 F g −1 at 60 A g −1 ), and acceptable cycling stability (3000 cycles at 10 A g −1 ) in a three-electrode assembly. The practical application of the composite electrode was investigated by an all-solid-state asymmetric supercapacitor cell using NiCo 2 O 4 /C-PANI/rGO as the cathode and activated carbon as the anode with specific capacitance of 262.5 F g −1 at 1 A g −1 and a good capacitance retention of 78% after 3500 cycles at an expanded working potential of 1.5 V. This work shows the importance of the composite assembly process that governs the microstructure of the composite.

Highly porous Co3O4/NiCo2O4 nanostructures were synthesized using zeolitic imidazolate framework-67 (ZIF-67) nanocrystals. The oxide composite structure was adjusted by modifying ZIF-67 crystallite size and the pore structure by the coordination modulation method. After forming the zeolite imidazolate framework-67 (ZIF-67)/Ni–Co layered double hydroxide intermediate composite through reaction with nickel nitrate, the intermediate composite was heated in air to result in Co3O4/NiCo2O4. Nitrogen adsorption was used for pore structure characterization of the template and resultant oxide composite. The maximum capacitance of nanostructured Co3O4/NiCo2O4 was 770 F g–1 at a discharge current density of 1 A g–1 with acceptable cycle stability, maintaining 70% of the initial capacitance after 10,000 charge–discharge cycles.

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Algae are a diverse group of aquatic organisms and have a potential to produce renewable biofuel via hydrothermal liquefaction (HTL). This study investigated the effects of reaction environments on biocrude production from “Tetraselmis sp.” algae strain by HTL process using red mud (RM) based catalyst. The inert (N2), ethylene (C2H4), reducing (10% H2/90% N2), and oxidizing (10% O2/90% N2) environments were applied to the non-catalytic as well as catalytic HTL treatments with two forms of RM catalysts: RM reduced at 500 °C (RRM) and nickel-supported RM (Ni/RM). Under nitrogen, ethylene and reducing environments, the biocrude yield increased by the following trend: No Catalyst < RRM < Ni/RM. The Ni/RM catalyst produced the highest biocrude yield (37 wt.%) in an ethylene environment, generated the lowest total acid number (14 mg KOH/g) under inert atmosphere, and lowered sulfur (33–66%) and oxygen (18–30%) from biocrude products irrespective of environments. The RRM catalyst maximized the biocrude carbon content (61 wt.%) under a reducing environment and minimized the heavy metal and phosphorus transfer from the feedstock to biocrude in studied ambiences. The reducing environment facilitated mild hydrotreatment during HTL reaction in the presence of RRM catalyst. Among the non-catalytic experiments, the reducing atmosphere optimized carbon content (54.3 wt.%) and calorific value (28 MJ/kg) with minimum oxygen amount (27.2 wt.%) in biocrudes.