The immiscible liquid|liquid interface is a unique platform that is often exploited for the assembly of NPs (Chem. Rev. 118 (2018) 3722); however, the use of NP modified electrified liquid|liquid interface is in its infancy. Our research program explored the capabilities of these interfaces and provided novel, breakthrough NP detection methodologies based on the liquid|liquid platform. Of particular interest is the water|ionic liquid (w|IL) interface, since NPs can be prepared within the IL with increased electroactivity owing to the absence of capping agents. Through this research program we pioneered electrochemical single NP detection through NP impacts at both the w|o and w|IL micro-interface; see Fig. 1 for the w|o Pt NP impact mechanism.
Investigative success is evidenced by 3 publications [Angew. Chem. 56 (2018) 13493; Chem. Rev. 118 (2018) 3722; Curr. Opin. Electrochem. 7 (2018) 200], with a fourth in review, and the ER being given an invited talk at 2018’s annual International Society of Electrochemistry Conference in Bologna (IT).
Through two synthetic methods we were able to generate both ILs and OIPCs in high yield and purity at low cost [Catal. Today 295 (2017) 89]. Subsequently, to investigate NP integration on OIPC/IL physicochemistry, Au and Pt NPs were prepared in IL and OIPC melt. Fig. 2 shows transmission electron microscopy images taken of Au and Pt NPs prepared in OIPC and IL. Using an electrolytic cell built in-house, the conductivity of IL-NP/OIPC-NP composites with different NP loadings, as well as thermal analysis, were used to investigate the effect of metal NPs on overall conductivity and phase transitions. Preliminary results suggest that with increased NP loading conductivity increases and solid-solid phase transitions merge and are reduced in intensity. More work is required however, one article is in preparation regarding the conducting/thermal influences of NP inclusion within ILs/OIPCs.
Our w|IL investigations showed that LiBH4, the reducing agent used to generate metal NPs within the IL phase, persisted in the IL phase and formed nanocrystals (NCs). Our high-resolution optical microscopies, such as dark-field and back-absorbing layer microscopy (BALM), allowed us to visualize these NCs, not possible with bright-field microscopies. The solubility of inorganic salts, like LiBH4, is rarely discussed but has wide implications on multiple applications, e.g. lithium ion batteries, industrial chemistry, and electrocatalysis. Therefore, a major outcome of this research was the discovery of reactive nanocrystalline inorganic salts formed within an IL phase. Moreover, LiBH4 is of use in two energy applications: H2 storage and in fuel cells. In this way, the LiBH4 NC-P66614NTf2 composite fluid could be used as a liquid fuel source. We also observed H2-in-IL bubble formation as a result of LiBH4 NC impacts. This research opens up an entirely new field of H2-in-IL micro-/nano-bubbles formation critical in water splitting for chemical fuel harvesting. Our strategy of incorporating opto-electronic techniques to observe operando H2 bubble formation, will be invaluable to research scientists in energy research. One publication (Electrochim. Acta. (2018) in review) and the ER’s invitation to speak at 2 other conferences (ECS fall meeting in Montreal, 2018; Chemistry Society of Canada annual meeting, summer 2019) have resulted from this work.
