“Design and Synthesis of 3D‐Ordered Mesoporous Co₃O₄ Nanostructures for Their Improved Supercapacitance and Photocatalytic Activity”

Abstract

We synthesized Co3O4 and Co3O4@Au‐NPs nano structures via simple and economical strategy for high‐performance supercapacitors. Co3O4@Au‐NPs modified glassy carbon electrode exhibited excellent electrochemical performance including high specific capacitance of 683 Fg−1(current density of 0.5 Ag−1), better retention capability of 65% at high current density (10 Ag−1) with remarkable cycling stability in 1000 continuous cycles at 0.5 Ag−1 current density (only 6% loss after 1000 cycles) and high energy and power densities (94.86 Whkg−1 and 3.48 kWkg−1). The photocatalytic activity of the synthesized mesoporous structures against Methylene Blue dye was also carried out and compared with the standard P25. The study showed that the presence of gold nanoparticles has increased the photocatalytic activity of synthesized porous Co3O4 to many folds. From the results it is believed that the addition of gold nanoparticles (Au‐NPs) has largely increased the supercapacitor and photocatalytic activity of Co3O4.

Co3O4/TiO2 Nanocomposite Formation Leads to Improvement in Ultraviolet–Visible-Infrared-Driven Thermocatalytic Activity Due to Photoactivation and Photocatalysis–Thermocatalysis Synergetic Effect

“…To improve its photocatalytic activity, several approaches were developed. The approaches involve increasing surface area by decreasing Co 3 O 4 nanoparticle size and preparing mesoporous Co 3 O 4 , 46,47 doping Co 3 O 4 with F or La, 62,63 forming nanocomposites with semiductor photoactalysts such as Ag 3 PO 4 , 43 BiOCl, 49 CuO, 53 BiVO 4 , 54 BiPO 4 , 55 Bi 2 WO 6 , 57 C 3 N 4 , 58,61 TiO 2 , 50,64−67 and so on. Among the literature, several groups tried to combine the advantages of both TiO 2 and Co 3 O 4 to improve the photocatalytic activity.…”

“…As thermocatalysts, Co 3 O 4 and its nanocomposites were reported to show good thermocatalytic activity for the abatement of air pollutants such as CO, methane, ethylene, volatile organic compounds (VOCs), and so on. − As a photocatalyst, it has a narrow bandgap of 1.2–2.1 eV, which provides a prerquisite to effectively utilize solar energy from UV and visible to near-infrared light. It is documented that Co 3 O 4 show photocatalytic activity for organic pollutant photodegradation, − water reduction and oxidation, − and CO 2 reduction , with UV or visible irradiation. But, pure bulk Co 3 O 4 is not a good photocatalyst due to its low photocatalytic activity.…”

“…To improve its photocatalytic activity, several approaches were developed. The approaches involve increasing surface area by decreasing Co 3 O 4 nanoparticle size and preparing mesoporous Co 3 O 4 , , doping Co 3 O 4 with F or La, , forming nanocomposites with semiductor photoactalysts such as Ag 3 PO 4 , BiOCl, CuO, BiVO 4 , BiPO 4 , Bi 2 WO 6 , C 3 N 4 , , TiO 2 , ,− and so on. Among the literature, several groups tried to combine the advantages of both TiO 2 and Co 3 O 4 to improve the photocatalytic activity. ,− For example, Bala et al reported that Co 3 O 4 /TiO 2 heterojunction formation greatly improved the photocatalytic activity for water reduction to produce H 2 under UV irradiation, which was attributed to the improvement of e – h separation efficiecny due to the transfer of holes from TiO 2 to Co 3 O 4 at the heterojunction .…”

“…This is mainly ascribed to lower oxidation potential of photogenrated holes in Co 3 O 4 (2.44 eV vs NHE), insufficient for oxidation of hydroxyl group ( · OH, H + /H 2 O = 2.73 V, pH = 7) and refractory organic pollutants with large oxidation potential. This is evidenced by the reported works: Although Co 3 O 4 and its nanocomposites show photocatalytic activity for the photodegration of easily degradable polutants such as dyes, isopropyl alcohol, − for the photodegradation of refactory poisonous benzene as one of typical air pollutants, it has no photocatalytic activity due to the large oxidation potential of benzene . Therefore, it is urgently needed and challenging to develop a novel strategy to perfectly utilize its good thermocatalytic activity and its wide optical absorption as a narrow band gap photocatalyst.…”