Direct Z-scheme construction of C2N/Mg(OH)2 heterojunction and first-principles investigation of photocatalytic water splitting

Abstract

Efficient water-splitting photocatalysts are pivotal in enhancing solar energy utilization to its maximum potential. Using first-principles calculations, the current study systematically explores the heterojunction's electron, carrier transfer, and optical properties. The observations indicate that the C2N/Mg(OH)2 heterojunction manifests a staggered band configuration, culminating in the accomplishment of a Z-type charge transfer paradigm. This mechanism promotes the recombination of e-h pairs within the C2N/Mg(OH)2 heterojunction, leading to the prolonged retention of photogenerated electrons in the Mg(OH)2 layer and photogenerated holes in the C2N layer. Consequently, this enables a sustained water reduction and oxidation reaction. The C2N/Mg(OH)2 heterojunction exhibits oxidation-reduction potentials that cross those of aqueous solutions under acidic (pH = 0) and neutral (pH = 7) conditions, thereby facilitating the photocatalytic process of water decomposition. Moreover, the optical absorption coefficient of the heterojunction surpasses that of a single two-dimensional material. Therefore, the direct Z-type C2N/Mg(OH)2 heterojunction holds promising potential as an exceptional photocatalyst for water decomposition.