Prefer-oriented Cu2O Micro-crystals: SAM Templated Growth and DMMP-vapor Detection

With self-assembled monolayer (SAM) as template, cubic cuprous-oxide (Cu2O) crystals with preferred orientation are obtained via simple and effective electrochemical redox process. Micro-region X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the as-grown Cu2O crystals. Besides uniform morphology and crystal size, the micro-crystals take preferred orientation that is strongly influences by the pre-modified SAM at substrate. The experiments indicate that the SAM not only acts as the growing template for the crystals, but also strongly affects the electrochemical redox process. To explore its sensing properties, the Cu2O crys- tals were grown onto a micro-cantilever to detect DMMP (dimethyl methylphosphonate) vapor. The sensing mecha- nism is complexation of phosphonyl group with Cu(I) that generates surface-stress at the cantilever surface. Tens of ppb DMMP vapor has been reproducibly detected.