Direct growth of ZnO crystals on various Cu substrates by Cu-catalyzed chemical bath deposition

Abstract

By the catalytic action of Cu on DMAB, ZnO crystals grow directly on various Cu substrates immersed in an aqueous solution containing zinc nitrate and dimethylamine borane at 80 °C under an ambient atmosphere.

Recent progress in the electrochemical deposition of ZnO nanowires: synthesis approaches and applications

“…During the past five decades, numerous reducing agents have been extensively used, including amino boranes, sodium borohydride, hydrazine, and sodium hypophosphite [120][121][122] . Although electroless deposition was originally designed as a process for depositing metals, it has since emerged as a simple, scalable, low-cost process for depositing ZnO nanowires and nanorods, one especially relevant to growing nanowires or nanorods on irregular, nonconductive, internal, and natural surfaces 6,123,124 .…”

“…In 1996, Izaki et al first proposed using electroless deposition to grow ZnO deposits [125][126][127] . Compared with other strategies involving chemical bath deposition (e.g., hexamethylenetetramine-based processes), electroless deposition allows the direct preferential growth of nanowires and nanorods without needing the otherwise necessary ZnO seed layer on the substrate.…”

“…Compared with other strategies involving chemical bath deposition (e.g., hexamethylenetetramine-based processes), electroless deposition allows the direct preferential growth of nanowires and nanorods without needing the otherwise necessary ZnO seed layer on the substrate. The electroless deposition of ZnO nanowires and nanorods typically involves using zinc nitrate as a precursor and dimethylamine borane (DMAB)-that is, (CH3)2NHBH3as a reducing agent at 50-80 °C 6,127 . Thus, a plausible mechanism of deposition can be written as 124,125,127,128 : Unlike electrodeposition, the electroless deposition of ZnO nanowires or nanorods is possible on nonconductive substrates, including glass, polymers, or natural surfaces.…”

“…The electroless deposition of ZnO nanowires and nanorods typically involves using zinc nitrate as a precursor and dimethylamine borane (DMAB)-that is, (CH3)2NHBH3as a reducing agent at 50-80 °C 6,127 . Thus, a plausible mechanism of deposition can be written as 124,125,127,128 : Unlike electrodeposition, the electroless deposition of ZnO nanowires or nanorods is possible on nonconductive substrates, including glass, polymers, or natural surfaces. Although the oxidation of the chemical reducing agent (e.g., DMAB) requires a catalytic surface to be initiated, such a surface can be easily provided by palladization, a process frequently used for the electroless deposition of metals 122,129 .…”

“…18), which induces the generation of hydroxide ions. In turn, the electrogenerated hydroxide ions drive the precipitation of Zn(OH)2, which ZnO dehydrates in a solid-solid phase transformation at moderate temperatures [125][126][127][128] . In parallel, the electrogenerated HBO2 (pKa = 9.24) and (CH3)2NH2 + (pKa = 10.77) can also help to maintain a pH near 9-10 in the substrate's vicinity.…”