Functional Materials Based on Well-Defined Colloidal Nanoscale Blocks for Applications in Sensing, Photoelectrochemistry, and Environmental Remediation

本研究旨在进一步发展可剪裁(根据尺寸、形状、表面和物理性质)的纳米级构建块(NBB)的合成和表征，特别是实现这些NBB的功能应用。目标应用包括基于等离子体共振和表面增强拉曼散射(SERS)的传感、光电化学、光催化和环境修复。 在过去的6年中，PI的实验室在合成控制尺寸和形状控制的纳米级积木(NBB)方面建立了经过验证的记录，重点是功能特性的优化，例如可调表面等离子体共振(SPR)。开发的NBBS的新颖性和实用功能源于自下而上的胶体合成在尺寸、形状和表面化学方面实现了精确控制。具体地说，对于SPR传感，PI的团队通过控制NBB胶体生长中的尺寸，合成了SPR共振位置精确到几nm以内的五角形银棒和小片；而优化的银十面体的尺寸选择导致了非常尖锐的SPR峰宽，这对SPR传感的灵敏度至关重要。对于表面增强拉曼光谱(SERS)的应用，银纳米粒子的尺寸控制，特别是对所形成的规则小平面形貌的纳米级空穴(5-50 nm)的精确合成裁剪，对于显示单个银纳米粒子显著的SERS增强是至关重要的。因此，下一阶段的研究建议是扩大NBB的范围，扩大其有用的功能性质的范围，并专注于其应用的实现(SPR，SERS)。 这项研究的三个主要方向是：i)进一步开发具有稳定性和SPR特性的特定用途的等离子体NBB；ii)合成用于光电化学应用的新型富电子氧化物NBB；以及iii)基于所开发的NBB生产原型传感器件。 I)对于银NBB的稳定性，研究小组将首先开发其金涂层，以利用金的稳定性，同时保留银的优势等离子体特性。其次，该团队将致力于用二氧化硅和聚合物对NBB进行封装，以提高稳定性和可定制的等离子性能。 Ii)对于导电氧化物NBB，研究小组首先从Ru和Ir的二氧化物开始，随后将重点转向成本优势的3D金属，如锰和铁氧化物。该团队的目标是在金属-超原子转变(大约20-200个原子团簇)附近实现可调的有利性质。 Iii)对于NBBS应用的实施，将与其他研究小组和行业合作伙伴合作，重点研究基于SPR和SERS的传感器原型开发。用于SPR传感的主要NBB包括镀金NBB和外壳NBB。 PI的小组目前处于通过所获得的NBB合成库来实现这些目标的最佳位置。 拟议研究的实际好处是利用在NBB合成方面开发的专业知识和能力，并进一步应用这些知识来创造新材料，其中精确的尺寸和表面控制对于实现先进的功能特性和应用绝对至关重要。基于所开发的NBB基材料的应用范围包括等离子体和SERS传感、光电化学、用于分解水的阳极以及基于氧化催化的环境修复。SPR传感将是当前的主要焦点。

The proposed research is aimed at further advancement of the synthesis and characterization of tailorable (by size, shape, surface, and physical properties) nanoscale building blocks (NBBs) and specifically at the realization of functional applications of these NBBs. Targeted applications include sensing based on plasmonic resonance and surface-enhanced Raman scattering (SERS), photoelectrochemistry, photocatalysis, and environmental remediation. During the last 6 years, the PI’s laboratory established a proven track-record in synthetic control over size- and shape-controlled nanoscale building blocks (NBBs) with the emphasis on optimization of functional properties, such as tuneable surface plasmon resonance (SPR). The novelty and utilizable functionality of the developed NBBs originate from the achieved precise control in size, shape, and surface chemistry imparted by the bottom-up colloidal synthesis. Specifically, for SPR sensing, the PI’s group synthesized silver pentagonal rods and platelets with the precise position of SPR resonance within a few nm through the size control in the NBB colloidal growth; while optimized size-selection of silver decahedra resulted in the remarkably sharp SPR peak width, crucial for the sensitivity of SPR sensing. For surface-enhanced Raman spectroscopy (SERS) applications, the size control of the silver nanoparticles, and especially the precise synthetic tailoring of the nanoscale cavities (5-50 nm) of the developed regular faceted morphologies, were crucial to demonstrate remarkable SERS enhancement by single silver nanoparticles. Consequently, the next phase of the proposed research is to expand the range of NBBs expanding on the range of their useful functional properties and to focus on realization of their applications (SPR, SERS) . Three major directions of the proposed research are i) further development of plasmonic NBBs with stability and SPR properties tailored for specific applications; ii) synthesis of novel electron-rich oxide NBBs for photoelectrochemical applications; and iii) production of prototype sensing devices based on the developed NBBs. i) For the stability of silver NBBs, the research team will first develop their coating with gold to take advantage of gold stability, while retaining advantageous plasmonic properties of silver. Secondly, the team will work on encapsulation of NBBs with silica and polymers for improved stability and tailorable plasmonic properties. ii) For the conductive oxide NBBs, the team first started with ruthenium and iridium dioxides and subsequently changed the emphasis to cost-advantageous 3d metals, such as manganese and iron oxides. The team aims at realizing tunable advantageous properties in the vicinity of the metal-superatom transition (at ca. 20-200 atoms clusters). iii) For the implementation of NBBs applications, the research will focus on prototype development of sensors based on SPR and SERS in collaboration with other research groups and industrial partners. Primary NBBs for SPR sensing include gold-plated and shell NBBs. The PI’s group is currently in the best position to accomplish these goals with the attained synthetic library of NBBs. Tangible benefits of the proposed research are in capitalizing on the developed expertise and capabilities in the synthesis of NBBs and further applying this knowledge to create novel materials where precise size- and surface-control is absolutely critical for the realization of advanced functional properties and applications. The range of applications based on the developed NBB-based materials includes plasmonic and SERS sensing, photoelectrochemistry, anodes for water splitting, and environmental remediation based on oxidative catalysis. SPR sensing will be the primary immediate focus.