In Silico Evaluation of Cellulose, Chitosan, and Metal Clusters (Cu18 and Au32) for Ethylene Control Material in Postharvest Agriculture

Effective ethylene (C2H4) control technology in postharvest agriculture is critical for minimizing crop wastage and improving supply chain efficiency. Here, we simulate the adsorption of C2H4 on cellulose, chitosan, copper cluster, and gold cluster using the framework of density functional theory. In all studied complexes, the adsorption processes of C2H4 are spontaneous, indicated by negative adsorption energies. The interaction of C2H4 with cellulose and chitosan is generally described as physisorption, where minimal orbital hybridization is visible and long-range interaction distances are measured. The low magnitude of adsorption energies yields a recovery time of 10-11-10-9 s at 298 K under UV incident radiation. The results of both copper and gold clusters show that the magnitude of adsorption can be in the regime of chemisorption and physisorption. In addition, the recovery time for copper and gold clusters can reach the range of 102 s and 101 s, respectively. The electron localization function and frontier orbitals revealed a strong hybridization between the copper and gold clusters with C2H4, further explaining the claim. The chemisorption character is also evident in the increased absorption intensities in the UV region of copper and gold clusters upon C2H4 adsorption. These observations are potential sensing properties of the metal cluster for ethylene. The analysis of the electronic density of states revealed that the copper and gold clusters generally maintain their metallicity after the attachment of the C2H4, except for minor broadening of peaks. The paper provides an in-depth perspective on C2H4 adsorption with biopolymers and metal clusters, providing future insights and clarifying previous experimental studies. These findings will serve as a reference for designing selective and low-cost materials for C2H4 regulation technologies in postharvest agriculture.