High-performance flexible hydrogen sensor based on atomic layer deposited Pd-decorated SnO2 thin films

The development of flexible hydrogen sensors compatible with micro-electro-mechanical system (MEMS) is critical for real-time monitoring in wearable device applications. However, conventional fabrication methods struggle to balance high sensitivity, low noble metal consumption, and mechanical robustness. Herein, a high-performance flexible hydrogen sensor was constructed on polyimide (PI) substrates using atomic layer deposited (ALD) Pd-decorated SnO 2 thin films . The impact of Pd cycles and operating temperature on the hydrogen sensing properties has been evaluated. The 40-cycle Pd@SnO 2 /PI sensor exhibits a high response of 1229.2 to 30 ppm H 2 at 150 °C, fast response/recovery time of 13 s/89 s and excellent selectivity. Its response enhances 89 times than pristine SnO 2 film one. The precise atomic-scale deposition of Pd nanoparticles via ALD can improve hydrogen sensitivity through catalytic and spill-over effects while minimizing Pd usage. The fully ALD-derived hydrogen sensor shows better robustness after 1000 bending cycles and reduces Pd loading amount with only 0.62 % coverage, demonstrating a breakthrough in cost-effective and durable hydrogen detection. All these manifest that ALD-derived Pd@SnO 2 /PI sensor may be a versatile approach to develop the flexible hydrogen sensors toward MEMS.