(Invited) ALD for Electrocatalysis and Sensor Applications

Abstract

Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt atoms anchored to graphene and N-doped graphene nanosheet using the atomic layer deposition (ALD) technique. HRTEM and EELS spectroscopy were employed to identify the single atoms. The novel catalyst exhibit significantly improved catalytic activity (up to 10 times) for methanol oxidation over that of the state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the excellent performance. This work is anticipated to form the basis for the exploration of a next generation of highly efficient single-atom catalysts for various applications.Recently, we employed ALD to deposit ultrathin ZnCox gas sensing film and to fabricate in-situ MEMS based gas sensors for the selective oxidation of H2S. The ALD ZnCo50 MEMS sensors show a high sensitivity to H2S even at 0.38 ppb. The heterojunction fabricated by in-situ surface decoration and the change of oxidation ability for selective oxidation of H2S offers a novel and simple strategy in the fabrication of MEMS-based gas sensors in a wafer level.