# Investigating SnOx/Graphene Oxide heterostructure for methane sensing and its application as a tunable light absorber for optoelectronic devices

## TL;DR

This paper explores SnOx/GO heterostructures for methane sensing and light absorption, showing their potential in optoelectronic and sensing applications.

## Contribution

The study introduces a tunable SnOx/GO heterostructure with optimized methane sensing and light absorption properties based on oxygen mole fraction and methane concentration.

## Key findings

- Type-C SnOx/GO heterostructures show the highest absorption coefficient for UV and visible light.
- Type-II heterostructures exhibit strong near-infrared absorption with the highest extinction coefficient at 1000 nm.
- CH₄ has higher stability and affinity for adsorption on SnOx/GO compared to other atmospheric gases like H₂O and CO₂.

## Abstract

This study investigates the optical and electronic properties of SnOx/Graphene Oxide (SnOx/GO) heterostructures, focusing on their sensitivity and selectivity to methane adsorption and its tunable light absorption capabilities across different wavelength ranges. By categorizing SnOx/GO heterostructures into four types based on the oxygen mole fraction (x) of SnOx, notable differences are observed in their light absorption, extinction coefficient, and reflectance. Among these, Type-C heterostructures demonstrate the highest absorption coefficient (~1.8 × 10⁵ cm ⁻ ¹), indicating strong potential for UV and visible light applications. Building upon the optimized Type-C SnOx/GO heterostructure, we further examine the effect of varying concentrations of methane molecules adsorbed on its surface. This leads to the classification of four additional heterostructure types- Type-I to Type-IV which are based on the methane molecules concentration adsorbed on the surface of an optimized SnOx/GO heterostructure. The interaction with methane further modulates the optoelectronic properties of heterostructure, with Type-II heterostructures demonstrating the highest extinction coefficient (~8.0 at 1000 nm) and strong near-infrared absorption. In contrast, Type-IV structures, characterized by the highest methane concentration, show a significant increase in reflectance (~0.85) and a reduction in absorption. Additionally, an energy distribution analysis of various atmospheric gases, such as CH₄, H₂O, and CO₂ were conducted to evaluate the selectivity of SnOx/GO heterostructure based sensors. The aim was to ensure minimal interference from other ambient gases. The analysis revealed that CH₄ exhibits a more negative energy state, indicating higher stability and a greater affinity for adsorption on the sensor surface compared to the other atmospheric gases. This stabilization highlights the interaction dynamics of the material, reinforcing its potential for diverse applications, including UV absorption, infrared transparency, and trace methane detection. Overall, these findings establish SnOx/GO heterostructures, particularly the Type-C variant with an optimal oxygen mole fraction (x), as promising candidates for advanced optical and methane gas-sensing technologies.