Atomic-Layer Deposition\nof the Single-Atom Pt Catalyst\non Vertical Graphene for H<sub>2</sub> Sensing

Single-atom catalysts have the advantage of high chemical\nefficiency,\nwhich requires atomic-scale control during catalyst formation. In\norder to address this challenge, this work explores the synthesis\nof single-atom platinum (SA-Pt) catalysts using atomic-layer deposition\n(ALD) on vertical graphene (VG), in which a large number of graphene\nedges serve as energetically favorable nucleation sites for SA-Pt,\nas predicted by density functional theory calculations. Interestingly,\nSA-Pt has been achieved on VGs at low ALD cycle numbers of up to 60.\nWith a further increase in the number of ALD cycles, an increasing\nnumber of Pt clusters with diameters <2 nm and Pt nanoparticles\n(NPs) with diameters >2 nm become dominant (nano-Pt @VG). This\nis\nin contrast to the observation of predominantly nano-Pt on other carbon\nnanostructures, such as carbon nanotubes and monolayer graphene, under\nthe same ALD growth conditions, indicating that the edge states on\nVG indeed play a critical role in facilitating the formation of SA-Pt.\nProfound differences are revealed in a comparative study on H<sub>2</sub> sensing. SA-Pt exhibits both a higher sensitivity and faster\nresponse than its nano-Pt counterpart by more than an order of magnitude,\nillustrating the high catalytic efficiency of SA-Pt and its potential\nfor gas sensing and a variety of other catalytic applications.