Photoelectrochemical Water‐Splitting Using CuO‐Based Electrodes for Hydrogen Production: A Review

Abstract

The cost‐effective, robust, and efficient electrocatalysts for photoelectrochemical (PEC) water‐splitting has been extensively studied over the past decade to address a solution for the energy crisis. The interesting physicochemical properties of CuO have introduced this promising photocathodic material among the few photocatalysts with a narrow bandgap. This photocatalyst has a high activity for the PEC hydrogen evolution reaction (HER) under simulated sunlight irradiation. Here, the recent advancements of CuO‐based photoelectrodes, including undoped CuO, doped CuO, and CuO composites, in the PEC water‐splitting field, are comprehensively studied. Moreover, the synthesis methods, characterization, and fundamental factors of each classification are discussed in detail. Apart from the exclusive characteristics of CuO‐based photoelectrodes, the PEC properties of CuO/2D materials, as groups of the growing nanocomposites in photocurrent‐generating devices, are discussed in separate sections. Regarding the particular attention paid to the CuO heterostructure photocathodes, the PEC water splitting application is reviewed and the properties of each group such as electronic structures, defects, bandgap, and hierarchical structures are critically assessed.

Architecture lattice‐matched cauliflower‐like CuO/ZnO p–n heterojunction toward efficient water splitting

“…9(b), which suggests that it could efficiently utilize light energy for the water splitting reaction. 48,49 The results demonstrate that efficient light absorption of CuO/ZnO would enhance its PEC performance.…”

Copper Oxide-Based Photocatalysts and Photocathodes: Fundamentals and Recent Advances

“…CuO physicochemical properties and its activity towards PEC water splitting have been very recently discussed in a dedicated review [ 12 ]. However, it is worth to summarize the main properties of CuO, because of its relevance in the topic discussed in the present work and for the frequent co-existence of Cu 2 O and CuO in promising photocathodes.…”

Metal–organic framework derived carbon-encapsulated hollow CuO/Cu2O heterostructure heterohedron as an efficient electrocatalyst for hydrogen evolution reaction

“…CuO has a narrow bandgap of 1.2–1.7 eV and Cu 2 O has around 1.9–2.2 eV. 13 Both CuO and Cu 2 O possess conduction band edges with suitable positions for potential H 2 O/H 2. Copper vacancies exist in CuO, and based on theoretical calculations, these copper vacancies are the most stable defects, which is beneficial for electrochemical activities.…”