Pd Nanocluster/Monolayer MoS₂ Heterojunctions for Light-Induced Room-Temperature Hydrogen Sensing

Developing sensing approaches that can exploit visible light for the detection of low-concentration hydrogen at room temperatures has become increasingly important for the safe use of hydrogen in many applications. In this study, heterostructures composed of monolayer MoS₂ and Pd nanoclusters (Pd/MoS₂) acting as photo- and hydrogen-sensitizers are successfully fabricated in a facile and scalable manner. The uniform deposition of morphologically isotropic Pd nanoclusters (11.5 ± 2.2 nm) on monolayer MoS₂ produces a plethora of active heterojunctions, effectively suppressing charge carrier recombination under light illumination. The dual photo- and hydrogen-sensitizing functionality of Pd/MoS₂ can enable its use as an active sensing layer in optoelectronic hydrogen sensors. Gas-sensing examinations reveal that the sensing performance of Pd/MoS₂ is enhanced three-fold under visible light illumination (17% for 140 ppm of H₂) in comparison with dark light (5% for 140 ppm of H₂). Photoactivation is also found to enable excellent sensing reversibility and reproducibility in the obtained sensor. As a proof-of-concept, the integration of Pd nanoclusters and monolayer MoS₂ can open a new avenue for light-induced hydrogen gas sensing at room temperature.