Comparative Study of H₂S Gas Sensing: Pristine vs. Cobalt-Functionalized C₂N Using First-Principles Modeling

The exceptional physical and electrical characteristics of two-dimensional Nitrogenated Holey Graphene (C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N) devices highlight their significance. C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N-based sensors demonstrate remarkable sensitivity, stability, and responsiveness compared to other solid-state sensors. The conductivity of C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N experiences shifts upon exposure to a wide array of organic and inorganic substances, enabling the detection of various target molecules through these conductivity alterations. Using first-principles transport simulations, a sensor device incorporating Nitrogenated Holey Graphene (C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N) is specifically designed to detect varying concentrations of hydrogen sulfide (H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>S) gas molecules. Through the utilization of the Quantumwise Atomistix Toolkit (ATK), a simulator for nanoscale semiconductor devices, a C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N-based sensor is simulated in this study. This work studies the effectiveness of C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N sensors, both pristine and functionalized with Co, for detecting varying concentrations of hydrogen sulfide (H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>S) gas molecules. Our findings reveal that the Co-functionalized C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N sensor performs better than the pristine counterpart. Through simulations, we demonstrate the sensor's ability to detect single and double H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>S molecules with 20% higher sensitivity and 15% improved selectivity compared to pristine C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N. This research highlights the potential of C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>N-based sensors in gas sensing applications, including environmental monitoring and industrial safety, and notably in biomedical applications such as medical diagnostics through breath analysis for disease markers. The effectiveness of employing density functional theory for sensor analysis and electronic transport calculations is also highlighted.