2D nanosheet SnS2 solution-processed photoanodes: Unveiling enhanced visible light absorption for solar fuels applications
Yudania Sánchez, Maxim Guc, Sara Martí-Sánchez, Maykel Jiménez-Guerra, Shadai Lugo-Loredo, Jordi Arbiol, Alejandro Perez-Rodriguez, Jordi Martorell, Carles Ros. (2024). 2D nanosheet SnS2 solution-processed photoanodes: Unveiling enhanced visible light absorption for solar fuels applications. International Journal of Hydrogen Energy, 77, 193–202. DOI: https://doi.org/https://doi.org/10.1016/j.ijhydene.2024.06.160
Abstract
The excessive band gap of metal oxide photoanodes currently poses a significant challenge to scaling up photoelectrochemical water splitting and CO2 reduction processes. However, metal sulfides with a 2D nanostructured morphology present a promising alternative, offering improved optoelectronic properties and catalytic capabilities in the oxygen evolution reaction (OER). Furthermore, this study breaks new ground by demonstrating, for the first time, the visible spectra absorption capabilities of SnxSy photoanodes. These photoanodes were fabricated using facile non-vacuum techniques and subsequently post-annealed in a sulfur atmosphere. This process yielded SnS2 multilayer nanosheets exhibiting remarkable visible-light absorption down to 900 nm wavelengths.
Annealing at an optimal temperature of 500 °C led to remarkable results, including photovoltages exceeding 1 V and photocurrents surpassing 1.6 mA/cm2 at 1.23VRHE. Moreover, we observed an impressive incident photon-to-current conversion efficiency (IPCE) of 75% at 330 nm. Notably, photon conversion within the 500–900 nm range (down to 1.37 eV) associates with a phase transformation from orthorhombic α-SnS to Sn2S3, and subsequently to hexagonal SnS2. Furthermore, IPCE plays a crucial role in elucidating effective phase transformation and photon conversion at wavelengths below the dominant direct band gap for SnS2. This observation suggests the potential existence of indirect transitions or confinement effects within the low-dimensional nanosheets. In conclusion, SnS2 nanosheets, fabricated through solution-processed methods, hold immense promise for the development of large-scale, cost-effective, and efficient photoelectrochemical devices.
