Electrochemical processing of discrete nanoparticle ions

在各种(分级)功能材料中，基础科学研究和技术应用都需要高质量、纯化的纳米颗粒。碳纳米管是一种典型的纳米粒子，如果剩余的加工障碍能够克服，它将具有巨大的前景。最近的一种方法是通过在金属-氨溶液中使用化学充电来形成“纳米管”阴离子来解决这一挑战。充电独一无二地提供了一种获得单壁纳米管真正热力学平衡解决方案的方法，并已被证明提供了一种去除无定形碳和分离金属与半导体部分的方法；这项技术已经获得商业许可，并成为一家新企业的主题。然而，在发展了这一方法后，我们意识到，通过使用纯电化学充电可以避免具有挑战性的碱金属-氨溶液。这种方法代表了一种全新的纳米颗粒加工策略，通过电化学溶解和随后的电沉积离散的纳米颗粒离子。我们相信，这种方法将是通用的，可能适用于各种电化学稳定的导电纳米颗粒，可能包括贵金属体系、石墨烯和一些过渡金属硫化物；它提供了无与伦比的电荷密度和化学势控制。这些结果提出了基本的科学问题，即离散纳米粒子电化学的可能性以及与传统原子/离子体系的潜在类比。他们还提出了涉及纳米颗粒的新的大规模制造工艺的机会，特别是提纯(分馏)、功能涂层或复合/杂化材料的共沉积。值得注意的是，许多大型工业过程依赖于电化学方法，包括铜的提纯和铝的电积。纳米粒子离子本身为进一步的化学反应或组装提供了机会。例如，纳米碳化物阴离子可以与亲电性反应，提供了一种高产率产生功能化单个物种的方法。精确操纵电荷密度和电势的能力，再加上对这些材料复杂状态密度的了解，将使这种新的化学被理解、控制和开发。简而言之，这个项目将探索一个新的方向：通过电化学处理形成定义明确的离散离子所带来的科学挑战和技术机会。

High quality, purified nanoparticles are required for both fundamental scientific studies and technological applications in a variety of (hierarchical) functional materials. Carbon nanotubes are an archetypical nanoparticle with enormous promise if the remaining processing hurdles can be overcome. One recent route addresses this challenge by using chemical charging in metal-ammonia solutions to form "nanotubide" anions. Charging uniquely provides an approach to true thermodynamic equilibrium solutions of single walled nanotubes, and has proved to offer a means both to remove amorphous carbon and to separate metallic from semiconducting fractions; this technology has already been licensed commercially and is the subject of a new venture. However, having developed this methodology, we realised that the challenging alkali metal-ammonia solution can be avoided by using pure electrochemical charging. This approach represents an entirely new strategy for nanoparticle processing, through electrochemical dissolution and subsequent electrodeposition of discrete nanoparticle ions. We believe that the approach will be general and may be applicable to a variety of electrochemically stable, conductive nanoparticles, likely including noble metal systems, graphene, and some transition metal chalcogenides; it offers unrivalled control of charge density and chemical potential. The results raise fundamental scientific questions about the possibility of discrete nanoparticle electrochemistry and potential analogies to traditional atomic/ionic systems. They also suggest opportunities for new large scale manufacturing processes involving nanoparticles, particularly purification (fractionation), functional coatings or co-deposition of composites/hybrids. It is worth noting that many large scale industrial processes rely on electrochemical approaches, including the purification of copper, and electrowinning of aluminium. The nanoparticle ions themselves offer opportunities for further chemical reactions or assembly. As an example, nanotubide anions are reactive to electrophiles, offering a means to generate functionalised individual species in high yield. The ability to manipulate charge density and potential accurately, coupled with an understanding of the complex density of states of these materials, will allow this new chemistry to be understood, controlled and exploited.In short, this project will explore a new direction: the scientific challenges and technological opportunities enabled by the formation of well-defined discrete ions through electrochemical processing.