The current study aimed to investigate the effect of counterions on hydrothermally synthesized hydrozincite (zinc hydroxide carbonate), which was thermally converted to generate ZnO nanostructures, which are an efficient nanoadsorbent for the removal of Reactive Black 5 (RB5) dye from wastewater. Hydrozincite nanospheres and flower-like structures were hydrothermally prepared using various zinc salts (sulfate, acetate, and nitrate) and ammonium carbonate in a molar ratio of 1 : 3, respectively, at 120 C for 3 h. The morphology and crystallite size of the hydrozincite precursor were effectively controlled via the parameters of the hydrothermal reaction. Interestingly, sulfate was the optimum counterion, as zinc sulfate salt produced pure hydrozincite nanospheres with the smallest crystallite size ($13.57 nm), which were consequently thermally decomposed at 400 C for 1 h to produce pure nanosized ZnO ($10 nm). The compositions of the as-synthesized products were determined by means of FT-IR, FE-SEM, HR-TEM, XRD, zeta potential, BET, and thermal analyses. An adsorption study showed a much higher adsorption capacity (80.9 mg g À1 ) of the as-prepared ZnO nanoparticles toward RB5 dye. The adsorption of RB5 dye followed pseudo-second-order kinetics. In addition, the equilibrium adsorption of RB5 dye was best described by a Langmuir isotherm model and the calculated thermodynamic parameters, DG 0 (from À4.027 to À7.533 kJ mol À1 ), DH 0 (30.798 kJ mol À1 ), and E a (29.105 kJ mol À1 ), indicate the spontaneous, endothermic, and physisorptive nature of the adsorption process.

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The electrocatalytic reduction of carbon dioxide (CO2RR) into value-added fuels is a promising initiative to overcome the adverse effects of CO2 on climate change. Most electrocatalysts studied, however, overlook the harmful mining practices used to extract these catalysts in pursuit of achieving high-performance. Repurposing scrap metals to use as alternative electrocatalysts would thus hold high privilege even at the compromise of high performance. In this work, we demonstrated the repurposing of scrap brass alloys with different Zn content for the conversion of CO2 into carbon monoxide and formate. The scrap alloys were activated towards CO2RR via simple annealing in air and made more selective towards CO production through galvanic replacement with Ag. Upon galvanic replacement with Ag, the scrap brass-based electrocatalysts showed enhanced current density for CO production with better selectivity towards the formation of CO. The density functional theory (DFT) calculations were used to elucidate the potential mechanism and selectivity of the scrap brass catalysts towards CO2RR. The d-band center in the different brass samples with different Zn content was elucidated.

We report on the optimized fabrication and electrochemical properties of ternary metal oxide (Ti-Mo-Ni-O) nanoparticles as electrochemical supercapacitor electrode materials. The structural, morphological, and elemental composition of the fabricated Ti-Mo-Ni-O...

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Owing to the increasing demand for sustainable and ecofriendly energy storage devices such as supercapacitors, it is vital to continuously search for highly stable and cost-effective electrode materials with high energy and power densities. Herein, a 3D/2D metal-free mesoporous composite of graphitic carbon nitride (GCN) and bioderived carbon (Bio-C x ) is investigated as an energy storage electrode material. This composite overcomes the low conductivity and low capacitance limitations of GCN while enjoying its high corrosion resistance, high nitrogen content, and unique 2D structure. The GCN/Bio-C x composite exhibits a fairly wide operating potential window of 1.2 V in 0.5 M H 2 SO 4 aqueous electrolyte with a high capacitance of 300 F/g at 1 A/g. This high performance was ascribed to the huge number of available active sites, large surface area, and the unique 3D/2D structure. The assembled device employing the GCN/ Bio-C x composite as the positive electrode and mesoporous nitrogen-doped carbon (MPNDC) as the negative electrode showed an ultrahigh-energy density of 53.72 Wh/kg and a power density of 900 W/kg. The GCN/Bio-C x //MPNDC device retains ∼100% of its initial capacitance after 13 000 charge/discharge cycles with 100% Columbic efficiency.