Investigation of the structural, optical and electrical properties of Ca²⁺ doped CuCoO₂ nanosheets

Abstract

The size of CCCaO nanosheets decreased with increasing Ca dopant concentration, due to Ca2+ substitution on the Cu+ site in CCO nanocrystals.

Surfactant-Modified Hydrothermal Synthesis of Ca-Doped CuCoO2 Nanosheets with Abundant Active Sites for Enhanced Electrocatalytic Oxygen Evolution

“…Therefore, the above results show the same phonon–phonon interaction of CCCO-P NSs compared with unmodified CCCO NSs. Notably, the A 1g Raman-active peaks for CCCO-P1, -P2, and -P3 NSs slightly shifted to a lower wavenumber compared to that of pure CuCoO 2 crystals . This result indicated the appearance of the same important structural evolution following the addition of PVP in CCCO-P crystals as that of the Ca 2+ dopants affected by the CuO bonds by partially substituting the Cu + sites.…”

“…Besides, the BJH adsorption average pore size for CCCO-P2 NSs was 19.25 nm, which is larger than that of CCCO-P1 (15.81 nm) and CCCO-P3 (17.34 nm). Compared with CCCO-2 NSs (22.75 m 2 g –1 and 18.01 nm), CCCO-P2 NSs possess a greater BET surface area and larger pore size, indicating the decreasing crystallite size of CCCO-P NSs with 5 atom % Ca dopant synthesized by PVP-assited hydrothermal method. It is worth noting that the high porosity and large surface area are conducive to mass transfer and to provide more active sites during the OER process .…”

“…Our group has reported the possible chemical compositions of CCCO NSs which could be ascribed to the two chemical formulas: Cu + 1– x Ca 2+ x Co 3+ 1– x +2 y □ y Co 2+ x –3y O 2 (3 atom % and 5 atom % Ca dopants; □: Co vacancy) and Cu + 1– x Ca 2+ x Co 3+ 1– x Co 2+ x O 2 (10 atom % Ca dopant) . It has been demonstrated that the intrinsic activity of the electrocatalysts would be related to the Co vacancies from experimental results and theoretical computations .…”

“…However, the OER is often considered as a blockage of water splitting due to the sluggish reaction kinetics, causing higher overpotential loss than that of the HER. − One of the useful solutions to promote water splitting becoming a practical energy storage technology is to explore and develop a high-efficient and low-cost OER catalyst for increasing the reaction rate or decreasing the overpotential for the OER. , Here, one of the most exciting research areas is developing non-noble metal oxide-based OER electrocatalysts working in alkaline solutions with superior catalytic performance, which can be comparable to that of noble metal oxide-based catalysts (i.e., IrO 2 and RuO 2 ). , Among these reported nonprecious metal oxides, copper-based delafossite oxides (CuBO 2 ) have been extensively investigated for the OER in alkaline media, where typical examples of B cations are Al 3+ , Ga 3+ , Cr 3+ , Fe 3+ , Mn 3+ , Co 3+ , and Sc 3+ . Delafossite oxides exhibit good electrical conductivity, wide band gap, high transparency, and favorable stability. − The amount of surface active sites can be dramatically boosted by shrinking catalyst particle sizes to the nanoscale . Therefore, nanosized CuBO 2 compounds as electro/photocatalysts can provide promising applications.…”

“…Additionally, Toyoda and co-workers investigated the relationships between the d-orbital splitting (including the e g and t 2g occupancies) of active B sites and the oxygen evolution reaction activity . Recently, our group has prepared Ca-doped CuCoO 2 nanosheets (CCCO NSs) and has proved that the Ca 2+ doping has a positive influence on the decreasing particle size and on improving the surface area of pure CuCoO 2 crystals . Moreover, Jung et al demonstrated that La 2 NiO 4 perovskite by doping Ca into the La site exhibited high OER activity in an aqueous alkaline electrolyte .…”