Document Type

Article

Publication Date

4-17-2024

Abstract

This study investigated the best phases of cobalt oxide for the photochemical and photoelectrochemical (PEC) water-splitting reaction. Cobalt oxide was produced via a hydrothermal process of cobalt nitrate hexahydrate and then annealed at different temperatures from 450 oC to 950 oC. The Co3O4 phase was produced during pre-annealing and annealing at 450 oC. The mixed phase of Co3O4 and CoO was produced during annealing at 550 oC and 650 oC, and pure CoO was produced during annealing from 750 oC to 950 oC. The Co3O4 phase produced the highest photocurrent density with a value of 1.15 mA cm-2 at a -0.4 V potential bias vs. Ag/AgCl. This value two times higher than that reported by other researchers at the same potential bias. Furthermore, the highest rate of hydrogen collected by Co3O4 was ~272.6 mmol h-1 g-1 after 8 h photocatalytic process. The amount of collected hydrogen was stable until 12 h of the process. paraphrase this paragraph. In terms of electrochemical performance, the Co3O4 phase exhibited the highest photocurrent density, registering at 1.15 mA cm-2 when assessed at a potential bias of 0.4 V vs. Ag/AgCl. This measurement notably surpassed values previously documented by other researchers operating under identical bias conditions, constituting a twofold enhancement. Additionally, the Co3O4 phase demonstrated remarkable efficiency in hydrogen production, with a peak rate recorded at approximately 272.6 mmol h-1 g-1 following an 8-hour photocatalytic process. Impressively, this rate of hydrogen collection remained stable throughout the duration of the 12-hour process, indicating the sustained efficacy of the Co3O4 phase in promoting the desired catalytic reactions. Through a systematic exploration of cobalt oxide phases generated at varying annealing temperatures, this study elucidated the superior electrochemical properties of the Co3O4 phase, particularly in terms of photocurrent density and hydrogen generation rates. These findings not only contribute to advancing the understanding of cobalt oxide's role in PEC water-splitting but also underscore the significance of phase control in optimizing catalytic performance for renewable energy applications.

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