Epitaxial Growth of Two-Dimensional Nonlayered AuCrS₂ Materials via Au-Assisted Chemical Vapor Deposition

Abstract

nonlayered transition metal dichalcogenide (TMD) materials are emergent platforms for various applications from catalysis to quantum devices. However, their limited availability and nonstraightforward synthesis methods hinder our understanding of these materials. Here, we present a novel technique for synthesizing 2D nonlayered AuCrS 2 via Auassisted chemical vapor deposition (CVD). Our detailed structural analysis reveals the layer-by-layer growth of [AuCrS 2 ] units atop an initial CrS 2 monolayer, with Au binding to the adjacent monolayer of CrS 2 , which is in stark contrast with the well-known metal intercalation mechanism in the synthesis of many other 2D nonlayered materials. Theoretical calculations further back the crucial role of Cr in increasing the mobility of Au species and strengthening the adsorption energy of Au on CrS 2 , thereby aiding the growth throughout the CVD process. Additionally, the resulting free-standing nanoporous AuCrS 2 (NP-AuCrS 2 ) exhibits exceptional electrocatalytic properties for the hydrogen evolution reaction.

Facile Coordination Transitions in AgCrX2 (X = S, Se): Unprecedented Electrostrain, Negative Piezoelectricity and Thermal Expansion

“…Herein another abnormal phenomenon is the emergence of ferroelectricity at elevated temperature that diminishes at low temperature, which is an exception to the long-established Landau–Devonshire phenomenological model where the ferroelectric polarization should be maximized at 0 K, and monotonously decrease with increasing temperature until it diminishes at the Curie temperature. Similar phenomena should also emerge in the same group compounds like AuCrS 2 with DI phase as the ground state, which can be further optimized via doping in Ag 1− x Au x CrS 2 .…”