Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template

Abstract

The decoration of (photo)electrodes for efficient photoresponse requires the use of electrocatalysts with good dispersion and high transparency for efficient light absorption by the photoelectrode. As a result of the ease of thermal evaporation and particulate self-assembly growth, the phthalocyanine molecular species can be uniformly deposited layer-by-layer on the surface of substrates. This structure can be used as a template to achieve a tunable amount of catalysts, high dispersion of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a phthalocyanine metal precursor. Cobalt phthalocyanine (CoPc) films with different thicknesses were deposited by thermal evaporation on different substrates. The films were annealed at 400 °C in air to form a material with the cobalt oxide phase. The final Co oxide catalysts exhibit high transparency after thermal treatment. Their OER measurements demonstrate well expected mass activity for OER. Thermally evaporated and treated transition metal oxide nanoparticles are attractive for the functionalization of (photo)anodes for water oxidation.

Recent Developments in Visible‐Light‐Absorbing Semitransparent Photoanodes for Tandem Cells Driving Solar Water Splitting

“…Ziani et al fabricated a transparent Co oxide electrocatalyst via thermal evaporation of cobalt phthalocyanine (CoPc) at room temperature followed by heat treatment for 30 min under air. [ 60 ] The CoPc structure can provide highly ordered molecular assembly without a complicated synthesis protocol, resulting in the deposition of amount‐tunable, ultrafine, regularly ordered, and transparent OER catalysts. The optimized CoPc electrocatalyst not only enhanced the photocurrent, but also shifted the onset potential of BiVO 4 /WO 3 from 0.5 to 0.1 V versus RHE.…”

“…In addition, the problems limiting the efficiency of the tandem cell are discussed. To overcome the problems, various modifications, such as other element doping, [53][54][55][56][57][58] electrocatalyst coating, [14,31,[59][60][61] and function layer inserting [62][63][64][65][66][67] have been demonstrated. Finally, this Review will introduce some efforts and the future perspective to allow PEC devices, such as tandem cells, to be one of the practical and efficient systems to obtain renewable energy resources.…”

A Permselective CeOx Coating To Improve the Stability of Oxygen Evolution Electrocatalysts

“…In an alternative approach, the deposition of CeO x was also conducted on CoO x nanoparticles (SEM images are shown in the Supporting Information, Figure S5) . An accelerated stability test was performed by cyclic voltammetry in 0.5 m phosphate buffer solution (pH 7) (Supporting Information, Figure S11).…”

New Avenues to Chemical Space for Energy Materials by the Molecular Precursor Approach

“…The highly transparent films of cobalt oxide demonstrated a similar performance for OER when compared with other cobalt‐based catalysts used to functionalize the surface of a BiVO 4 /WO 3 photoanode. [ 86 ] In a recent study by Swierk and Don Tilley from 2018, a Co[N(SiMe 3 ) 2 ] 2 precursor was prepared and directly deposited onto indium‐tin‐oxide (ITO) electrodes from toluene in a glove box. The precursor was allowed to graft for 1 h and dried with a stream of nitrogen, followed by heating at 300 °C in air to decompose the precursor.…”