Abstract
Quartz nucleation normally requires harsh conditions; for instance, hydrothermal processes at 200–300 °C and 15–100 bar, where the high growth rate precludes selective formation of nanometer-sized quartz. Under ambient conditions, even quartz growth is considered to occur exceedingly slowly, requiring yearly timescales. Here we show that nanoquartz of size 1–5 nm can be nucleated from microemulsions under ambient conditions within 2 days. The nanoquartz particles are grown and annealed under mild hydrothermal conditions of 175 °C and autogenic pressure. This enables nanoquartz of size <10 nm and controllable structure to be obtained exclusively. Surface defects play a key role in determining the catalytic properties of the nanoquartz. Consequently, a similar two-stage microemulsion-hydrothermal synthesis strategy could provide significant benefits in optimizing nanocrystal catalysts.
Highlights
Quartz nucleation normally requires harsh conditions; for instance, hydrothermal processes at 200–300 °C and [15–100] bar, where the high growth rate precludes selective formation of nanometer-sized quartz
TEM studies on Span® 80 and Brij® 30 (SB) microemulsion aliquots established the formation of α-quartz nanocrystals as the majority silica phase present in microemulsions containing 5 μl g−1 sodium metasilicate (SMS) solutions of
0.31 and 0.19 nm spacings were observed, attributable to the {111} and {220} strongest diffracting planes of silicon, since it is known that α-quartz can beam damage and reduce to silicon under even relatively low intensity electron beams[22]
Summary
Quartz nucleation normally requires harsh conditions; for instance, hydrothermal processes at 200–300 °C and [15–100] bar, where the high growth rate precludes selective formation of nanometer-sized quartz. The nanoquartz particles are grown and annealed under mild hydrothermal conditions of 175 °C and autogenic pressure This enables nanoquartz of size
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