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

Abstract

It is urgent to explore cost-effective, high-efficiency, and durable electrocatalysts for electrochemical water splitting due to the rapidly increasing energy consumption. In this work, we successfully synthesize Ca-doped CuCoO2 nanosheets (CCCO-P NSs) with different Ca2+ dopants (such as 3, 5, and 10 atom %) by a surfactant-modified hydrothermal reaction with polyvinylpyrrolidone (PVP) addition. The oxygen evolution reaction (OER) performances of these CCCO-P NSs in 1.0 M KOH are investigated. An optimal nickel foam supported CCCO-P2 NSs (Ni@CCCO-P2, 5 atom % Ca-doped) electrode requires low overpotential of 470 mV to afford the current density of 10 mA cm–2 and small Tafel slope of 96.5 mV dec–1. Furthermore, the Ni@CCCO-P2 electrode displays outstanding long-term stability during the galvanostatic OER electrolysis for 18 h with a little degradation of 32 mV. The improvement of OER performances for CCCO-P2 NSs could be attributed to their higher active surface area, more active sites (Co vacancies defect and Co3+/Co4+ redox pairs), and higher electrical conductivity. This work highlights the joint effect of surfactant and Ca doping for preparing CuCoO2 with nanosheet-like morphology and porous crystal structure, which is favorable for enhancing their OER performance.

Hollow V-Doped CoMx (M = P, S, O) Nanoboxes as Efficient OER Electrocatalysts for Overall Water Splitting

“…Moreover, the highly open 3D nanobox structure could also guarantee a fast mass and electron transfer, thereby enhancing the OER performance. More importantly, after the successful incorporation of V, the electronic structure of Co was greatly modulated, which could offer a favorable surface electronic environment for the adsorption of reaction intermediates (*O, *OH, and *OOH), thus promoting the formation of O 2 . − …”

The Pivotal Role of s‐, p‐, and f‐Block Metals in Water Electrolysis: Status Quo and Perspectives

“…Among these lean metals, those referred to Al, Ga, Sn, and Bi are usually utilized for the OER and HER catalysis, and they improve the OER and HER activity in terms of the following aspects. [ 103,105,206–231 ] i) These lean metals can be readily etched in both the alkaline and acidic solutions, generating beneficial results including the formation of pores and partial phase reconstruction. ii) They can be prone to hybrid with other metals to form the (ordered) intermetallics with high conductivity.…”

“…As previously claimed in reports, one can dope NNTM-based catalysts with SPFMs and these metallic species can perform very well when combined with oxides. [229][230][231][232] In such oxides, a dynamic phase reconstruction can easily be triggered during OER when the metal leaching rate is slower than that of the metal deposition. In oxides, oxygen vacancies always exist, which sometimes leads to another possible catalytic mechanism, namely, the LOM, which is different from the abovementioned AEM.…”

Hydrothermal synthesized delafossite CuGaO2 as an electrocatalyst for water oxidation

“…A new class of transition metal oxides, delafossite materials (ABO 2 ), have also shown great potential for electrocatalytic applications, such as CuFeO 2 [20]. CuCoO 2 [21][22][23], CuMnO 2 [24]. Zhang et al [25] have successfully customized the surface charge of silver delafossite AgCoO 2 by adjusting the surface charge transfer state and transferring it into an efficient OER catalyst.…”

“…Since 2015, our team has been working on the hydrothermal synthesis of oxides, and we have successfully synthesized CuAlO 2 [31], CuCrO 2 [32,33], CuFeO 2 [34,35], CuMnO 2 [36,37], CuScO 2 [38], CuCoO 2 [21-23, 39, 40]. Du et al [21] synthesized Ca doped CuCoO 2 via a simple polyvinylpyrrolidone-assisted hydrothermal process, which required an overpotential of 470 mV to achieve a current density of 10 mA/cm 2 and a small Tafel slope of 96.5 mV/ dec in alkaline solution for OER. Deng et al [38] synthesized CuScO 2 by a hydrothermal method.…”