Optimized palladium-loaded tin-selenide sensor detects nitrogen dioxide at room temperature

When using gas sensors for environmental monitoring, two-dimensional materials like tin selenide have shown promise for devices due to their high surface area and potential for working at room temperature. Such 2D materials, however, often suffer from sluggish response and recovery kinetics that hinder their practical reliability. Increasing their sensitivity with noble metal catalysts such as palladium may boost performance, although the mechanism of action remains incompletely understood, preventing rational design and optimization of the functionalization.

Chen et al. have developed a nitrogen dioxide sensor based on tin selenide that demonstrates improved performance and sheds new light on the process of noble metal catalyst sensitization. Combining a solvothermal method with atomic layer deposition (ALD), researchers deposited palladium nanoparticles into a tin selenide/tin oxide heterostructure.

“While constructing heterojunctions with noble metals is not entirely new, the precise and controlled functionalization of a tin selenide/tin oxide heterostructure with palladium using ALD represents a significant step in material design, allowing for performance optimization by fine-tuning catalyst loading,” said author Jun Zhang. “More importantly, the innovative core lies in the comprehensive use of experimental data and DFT calculations to explicitly unravel the noble metal’s role.”

Gas sensing tests showed the palladium-optimized sensor performed exceptionally at room temperature in detecting nitrogen dioxide. Able to detect as little as 21 parts per billion, the device could respond within seven seconds and recover completely within 19 seconds. Its measured response of 21.9 to 5 parts per million of nitrogen dioxide marked a threefold improvement over unmodified 2D materials.

Calculations showed a synergistic effect between the n-n heterojunction structure and palladium’s dual role, providing both electronic and chemical sensitization.

The group looks to further explore sensitization mechanisms.

Source: “Dual-sensitization mechanism in Pd-SnSe₂/SnO₂ heterostructures for humidity-resistant NO₂ sensing at room temperature,” by Yilin Chen, Wenyang Zheng, Xiao Chang, Xianghong Liu, and Jun Zhang, Applied Physics Letters (2025). The article can be accessed at https://doi.org/10.1063/5.0297641 .