Oxygen-Doped GrapheneNanoribbons with High CatalyticPerformance in Chemical Etching of Silicon

Metal-assisted chemical etching (MacEtch) is a widely employed technique for fabricating silicon nanostructures, where the silicon covered by the metal catalyst is oxidized by hydrogen peroxide and subsequently etched by hydrofluoric acid. However, contamination from residual metal particles remains a significant challenge for the application of silicon devices. Carbon-based catalysts are gaining attention as promising alternatives to metal catalysts due to their lower cost and minimal contamination risks. One remaining issue is that their catalytic performance is significantly lower than that of noble metals. Our recent research has revealed that oxygen-doped 5-armchair graphene nanoribbons (5A-OGNRs), with the doping introduced by the –OC₄H₉ substituent, exhibit superior catalytic performance to gold in vapor-phase silicon etching. In this work, to elucidate the underlying mechanisms behind this high catalytic activity of 5A-OGNRs, we conducted theoretical studies using density functional theory calculations focused on the hydrogen peroxide reduction process, a critical step in silicon etching. The results reveal that oxygen doping generates high charge-density active sites on neighboring carbon atoms, significantly increasing the affinity for hydrogen peroxide adsorption on 5A-OGNRs. Furthermore, transition state calculations show that the activation energy for the hydrogen peroxide reduction reaction is lower when catalyzed by 5A-OGNRs than undoped 5-armchair graphene nanoribbons (5A-GNRs) and 7-armchair graphene nanoribbons (7A-GNRs), further enhancing catalytic performance. These results show the potential of oxygen-doped GNRs, particularly 5A-OGNRs, as highly efficient and cost-effective alternatives to metal-based catalysts for silicon etching in industrial applications.