Sustainable scalable synthesis of sulfide nanocrystals at low cost with an ionic liquid sulfur precursor

Abstract

Increasing the sustainability of nanocrystals is crucial to their application and the protection of the environment. Sulfur precursors for their synthesis are commonly obtained through multiple steps from H2S, only to be converted back to H2S during the synthesis of the nanocrystals. This convoluted process requires energy, reduces yields, increases waste and auxiliaries, and complicates recycling. Using H2S directly could drastically improve sustainability, but is prevented by toxicity and handling. We here show that H2S is stabilized by reaction with oleylamine (the most common and versatile ligand in nanoparticle synthesis) to form an ionic liquid precursor that addresses all major principles of green chemistry: it is made in one exothermic step, it leaves the reaction yielding a safer product and allowing the separate recycling of the precursors, and it produces high quality nanocrystals with high yields (sulfur yield > 70%) and concentrations (90 g L−1) in ambient conditions.

A highly selective electron affinity facilitated H2S sensor: the marriage of tris(keto-hydrazone) and an organic field-effect transistor

“…These transferred HS À ions tend to trap the holes (q) in the conduction channel via electrostatic attraction, which causes a significant positive shift in the threshold voltage (V TH ). This is confirmed with the help of the mathematical relation between the charges (q) in the channel and V TH , as can be seen in eqn (1).…”

“…The ultra-thin smooth M1 film with angstrom-(Å-) sized pores can allow these HS À anions to enter the M1 bulk region. As a result, these anions can trap the holes from the channel region, thereby causing a concurrent positive shift in threshold voltage and a reduction in drain current due to reduced holes (q) in eqn (1). Therefore, we speculate that the cumulative effect of the proposed mechanisms plays a pivotal role in achieving good sensing performance of the D4 OFET sensor.…”

“…Hydrogen sulfide (H 2 S) is a colorless, corrosive, malodorous, and poisonous gaseous substance often encountered in hotsprings and during the production of crude-petroleum products, as well as while refining natural gases. 1,2 At low concentration levels, exogenous H 2 S inhalation improves neurological functions and cardiac conditions. 3 High doses (o 10 ppm) cause eye irritation and fatigue, and exposure to levels 4 100 ppm results in severe neurological damage and cardiovascular conditions.…”

Growth of Colloidal Nanocrystals by Liquid‐Like Coalescence**

“…The number‐averaged particle volume was obtained with “total particle volume/total number of particles”. The reaction yield of the limiting reagent (sulfur in this study) was obtained with “100 %×actual yield/theoretical yield” [9] …”

Growth of Colloidal Nanocrystals by Liquid‐Like Coalescence**

“…Such experiments unfortunately are complicated by the concurrence of several mechanisms of growth (secondary nucleation, addition, aggregation, Ostwald ripening), [5b,f, 7] and the difficulty or impossibility of accurately measuring both particle sizes,shapes,and concentrations in time. [5a, 8] We developed am odel reaction system, the reaction between oleylammonium hydrosulfide (OLAHS) and PbCl 2 in oleylamine (OLA) to form PbS nanocrystals, [9] to investigate crystal-crystal coalescence in detail. We conducted reactions by injecting OLAHS into the PbCl 2 /OLA slurries at five different temperatures (80, 100, 120, 140, and 160 8 8C), and characterized the products at sixteen reaction times (1,2,4,6,8,10,12,14,16,20,24,30,36,42,50, and 60 min).…”