Single-layer ZnMN₂ (M = Si, Ge, Sn) zinc nitrides as promising photocatalysts

Abstract

Searching for two-dimensional semiconductor materials that are suitable for visible-light photocatalytic water splitting provides a sustainable solution to deal with the future energy crisis and environmental problems. Herein, based on first-principles calculations, single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides are proposed as efficient photocatalysts for water splitting. Stability analyses show that the single-layer ZnMN2 zinc nitrides exhibit energetic and dynamical stability. The electronic properties reveal that all of the single-layer ZnMN2 zinc nitrides are semiconductors. Interestingly, single-layer ZnSnN2 is a direct band gap semiconductor with a desirable band gap (1.74 eV), and the optical adsorption spectrum confirms its optical absorption in the visible light region. The hydrogen evolution reaction (HER) calculations show that the catalytic activity for single-layer ZnMN2 (M = Ge, Sn) is better than that of single-layer ZnSiN2. Furthermore, the band gaps and band edge positions for the single-layer ZnMN2 zinc nitrides can be effectively tuned by biaxial strain. Especially, single-layer ZnGeN2 can be effectively tuned to match better with the redox potentials of water and enhance the light absorption in the visible light region at a tensile strain of 5%, which is confirmed by the corresponding optical absorption spectrum. Our results provide guidance for experimental synthesis efforts and future searches for single-layer materials suitable for photocatalytic water splitting.

Point Defects in a Two-Dimensional ZnSnN2 Nanosheet: A First-Principles Study on the Electronic and Magnetic Properties

“…The optimized lattice constant and bond lengths are in good agreement with previous results. 46 The dynamical stability of the ZSN is verified by calculating its phonon band dispersion, which is depicted in Figure 1b. The monolayer of ZSN is found to possess dynamical stability in its free-standing form as examined by the phonon band dispersions through the whole BZ.…”

Utilizing Site Disorder in the Development of New Energy-Relevant Semiconductors

“…121 Recent computational work has predicted that singlelayer Zn−IV−N 2 compounds could be used for water-splitting applications. 122 Related materials, such as Zn 2 SbN 3 , have been identified as candidates for one of the water-splitting half reactions, in this case the hydrogen evolution reaction, rather than overall water splitting. 123 While cation ordering has yet to be investigated in materials for these applications, the band gap tuning described above for LED and PV applications could also be employed to modify band gap for these applications, possibly allowing tuning of band edge positions to improve particular photocatalytic reactions.…”

“…Among these, ZnGeN 2 is the most well-explored, mainly in the form Zn 1– x Ge x N 2– y O y , which has been shown to be an effective catalyst for overall water splitting. , It has also been identified as a candidate material for some CO 2 reduction processes , and for pollutant decomposition under visible light . Recent computational work has predicted that single-layer Zn–IV–N 2 compounds could be used for water-splitting applications . Related materials, such as Zn 2 SbN 3 , have been identified as candidates for one of the water-splitting half reactions, in this case the hydrogen evolution reaction, rather than overall water splitting .…”

The mechanism of enhanced photocatalytic activity for water-splitting of ReS2 by strain and electric field engineering

“…In particular, mechanical strain or an external electric eld are effective and practical ways to adjust the electronic properties of a 2D semiconductor. [45][46][47][48][49][50][51][52] For example, Bai et al have shown that single-layer ZnGeN 2 could be effectively tuned to provide a better match with the redox potentials of water and to enhance light absorption in the visible-light region at a tensile strain of 5%. 49 Edalati et al suggested that CsTaO 3 and LiTaO 3 exhibited optical bandgap narrowing and $2.5 times enhancement of photocatalytic hydrogen generation by straining.…”

“…[45][46][47][48][49][50][51][52] For example, Bai et al have shown that single-layer ZnGeN 2 could be effectively tuned to provide a better match with the redox potentials of water and to enhance light absorption in the visible-light region at a tensile strain of 5%. 49 Edalati et al suggested that CsTaO 3 and LiTaO 3 exhibited optical bandgap narrowing and $2.5 times enhancement of photocatalytic hydrogen generation by straining. 50 Wang et al reported that the biaxial strain tuned the bandgap and band alignment of a 2D CdS/ g-C 3 N 4 heterostructure for visible-light photocatalytic water splitting and accelerated the separation of photogenerated carriers and improved the photocatalytic activity.…”