Citrate-assisted one-pot assembly of palladium nanoparticles onto ZnO nanorods for CO sensing application

• Pd NPs (∼5 nm) functionalized ZnO NRs were synthesized by one step solution method.
• The response of Pd/ZnO NRs was two times higher than bare ZnO NRs.
• The response increased with temperatures as well as CO concentrations.
• Pd NPs increased depletion layer formation in Pd/ZnO as compared to ZnO NRs.
• High response of Pd/ZnO NRs was attributed to electronic as well as chemical sensitization of Pd NPs.

A facile one-pot strategy was developed for functionalization of palladium nanoparticles (Pd NPs) onto single crystalline ZnO nanorods (NRs). ZnO NRs (150–200 nm in length and 20–25 nm diameters) were synthesized by the solvothermal method, whereas the Pd NPs (below 5 nm) were deposited on the surface of ZnO NRs by the solution growth method. Sensor fabricated by the Pd/ZnO NRs showed significantly enhanced sensing performance as compared to pristine ZnO NRs. The increase in response of ZnO NRs after Pd NPs loading was attributed to electronic as well as chemical sensitization of Pd NPs.