Geoffrey Ozin教授Wiley专访：小材料，大影响

纳米人

2020-09-08

Ozin教授是一位著名的纳米化学家,也是Wiely旗下Advanced Science News (ASN)的一名长期专栏作者。他在裸金属原子团簇、沸石封装催化、纳米马达、光子晶体的最初合成、太空微重力环境结晶、纳米硅绿色化学、太阳能燃料等领域均有里程碑意义的发现。在他77岁生日之际，Ozin教授接受了ASN的采访并向大家介绍他多彩的学术职业生涯，目前的研究项目，和未来的计划。 本文翻译了采访的部分要点，而对于学术性较强的内容则附上Ozin教授英文原文，留给读者自己仔细品评。

问：在您学术生涯初期，您是一位材料化学家。请问您是如何开始涉猎“纳米化学”方向？

When you first started out, you were working as a materials chemist. How did you get involved in “nanochemistry”?

我其实是偶然进入纳米化学方向。当时的工作内容是围绕着这个领域的基础研究，之后这个领域才被大家称为纳米化学。

纳米化学：在消逝维度下的材料合成，Ozin教授在1992年发表于 Advanced Materials的一篇里程碑佳作 

由Thomas Graham (1805-1869) 开创的胶体化学在发展了近百年后，在70年代早期逐渐演变成为如今的纳米化学，与此同时，由Wolfgang Ostwald (1883-1943)掀起的胶体科学也开始演变成如今的纳米科学。Thomas Graham描述了物质在纳米到微米大小范围内的独特行为，而Wolfgang Ostwald 在他的著作“The World of Neglected Dimensions” (1914)中丰富了这一主题。当时我还是多伦多大学化学系的助理教授， 他们的工作启发我使用自下而上的化学方法来解决纳米维度下材料的自组装这一挑战。

但是，作为一名合成化学家，我面临一个重要且还未被解决的难题是：如何使用化学方法来制备尺寸在纳米级别（1-100 nm）的金属，半导体和绝缘体？我研究了这些材料在尺寸上的可调谐行为，并阐明其结构、性能、功能之间的关系并确定其应用方向。在低温下用裸露的金属原子进行化学反应启发了我通过在允许纳米团簇于固体基质中自扩散组装的方式，来实现在原子级别控制金属锰纳米团簇的结晶和生长过程。这个具有科学意义的壮举以前从未被实现过。通过这一方式， 我观察到了金属原子的成核和生长反应，并首次监测和量化了它们的聚集动力学。此外，我确认了当有不同小分子配体存在下的裸露金属原子或少量金属原子组成的纳米簇中，我们可以观察到当时未知的新型M_nL_m化合物。

问：列举一个在你职业生涯的初期你最喜欢的项目

What is one of your favorite early-career projects?

裸金属原子团簇化学奠定纳米化学基础。

One of my favorite early initiatives, undertaken while I worked as a Fairchild Fellow at Caltech in 1977 with William Goddard, was an experimental and theoretical study of Ni_n(C₂H₄)_m. This described for the first time the chemistry of “naked” nickel atoms and nickel clusters with ethylene, envisioning them as a localized bonding model for ethylene chemisorbed on bulk nickel. The ingenuity behind these 1970’s experiments, and expanded upon in my later papers, unveiled an unprecedented view of controlled size metal nanoclusters, the synthesis of which enabled the first explorations of the transition from molecular to quantum confined to bulk forms of metals. They also provided a unique platform for investigating cluster-surface relations. It is worth mentioning that I later enriched this work with the discovery of a collection of unprecedented metal atom and metal cluster photo-processes. These processes included naked metal atom photo-aggregation, naked metal cluster photo-dissociation and naked metal cluster photo-isomerization reactions as well as naked metal atom photo-insertion reactions into the carbon-hydrogen bonds of saturated hydrocarbons, such as methane.

Together, these early experiments on the chemistry and photochemistry of naked metal atoms and naked metal clusters, laid the groundwork for the development of the field of nanochemistry. The instrumentation to perform this kind of metal-atom-metal-vapor chemistry was manufactured and commercialized by a spin-off from my group, www.torrovap.com that was founded in 1981 and is still in business.

问：在奠定了裸金属原子金属团簇化学的基础之后，您的研究方向是如何发展的？

Where did your research take you after laying down this foundational groundwork in naked metal atom metal cluster chemistry?

沸石材料科学的先驱性工作。

My desire to take the insights gained from the nanochemistry work on naked metal atom and naked metal cluster cryochemistry “out of the cold” provided the link between my early work and the field of zeolite science. I envisioned making and stabilizing these tiny pieces of matter so that detailed studies of their structure, property, function, utility and relations could be undertaken. In this context, it occurred that because these M_n and M_nL_m nanoclusters were inherently metastable with respect to further agglomeration to thermodynamically stable bulk materials, they had to be stabilized by some kind of surface protecting sheath. I performed the nucleation and growth reactions within the nanometer-sized voids of zeolites, thereby “capping and trapping” the nanoclusters in a zeolite ligand cage, confirming that zeolites could serve as nanoporous hosts for synthesizing and stabilizing metal and semiconductor nanomaterials. 

During this period, thinking within the zeolite community focused solely on the properties and applications of zeolites in catalysis and gas separation. I, however, preferred to look at zeolites as solids filled with nanoscale voids and wondered how they could perform and compete in the advanced materials research space. I saw their potential in areas such as information storage, photovoltaics, batteries, fuel cells, photocatalyts, chemical sensors and drug delivery systems. Exploring this potential, I worked with Edith Flanigen at Union Carbide, Tarrytown, New York for five years to bring some of these ideas to practical fruition, ultimately describing my vision for the future direction of the field in the paper “Advanced Zeolite Materials Science”.

Coincidentally, around this time the Union Carbide team made the extraordinary discovery that nanoporous materials could be made from elements across the periodic table, thus expanding the composition field of zeolites way beyond aluminosilicates and silicates, inspiring me to focus attention on advanced materials applications of nanoporous metal chalcogenides, which I envisioned as self-assembled semiconductors filled with nanometer holes with perceived utility in molecular size- and shape-discriminating sensing devices enabling the development of an early “electronic nose”. To improve their crystalline perfection, I took self-assembly of these nanoporous semiconductor materials into space to see the effect of gravity on the nucleation and growth process.

问：在太空中发生了什么？

What happened in space?

太空微重力环境下的晶体生长。

This was a highlight of my early career, scientifically exhilarating and technologically demanding. The project was a collaboration between the Canadian Space Agency and the National Aeronautical Space Agency, structured around earth and space-based research. The former was conducted in my research group at the University of Toronto, the latter performed robotically in a get-away-special on May 19, 1996 NASA space shuttle Endeavor, STS 77. This mission is credited as the maiden flight geared towards microgravity research and the commercialization of space. Coincidentally, one of the shuttles crew was mission specialist Canadian Marc Garneau, who became a member of the Canadian parliament in 2008. The goal of the project was to study the effect of microgravity on the crystallization of layered microporous tin(IV) sulphides. This material was selected because its crystal structure is determined by weak inter-layer and strong intra-layer covalent bonds and its self-assembly was expected to be very sensitive to the nucleation and growth conditions. The outcome of five years of inspiring research was the discovery that in the absence of sedimentation and convection gravity driven disturbances of crystal growth under microgravity conditions, we observed improved overall crystal quality, exemplified by more well-defined morphologies with smoother facets, enhanced crystallinity, optical quality and void volume, compared to the crystals produced on Earth.

问：这如何导致了纳米化学的诞生？

How did this lead to the birth of nanochemistry?

1992年的展望工作，将纳米技术与化学概念真正结合。

In hindsight, my ensuing research laid out the essence of a chemical approach to nanomaterials — a futuristic field that I called “nanochemistry”. This paper set the scene for a nanomaterials revolution that continues unabated today. I envisioned the novel world of nanochemistry with its 0D dots, 1D wires, 2D layers, and 3D open frames, with configurations that surprised, and shape- and size-dependent behaviors that startled. Here were the conceptual foundations, the description of a bottom-up paradigm for synthesizing nanoscale materials with nanometer-level command over their size, shape, surface, and self-assembly. The potential I saw was breathtaking. It would be possible to produce nanoscale materials — perfect down to the last atom — from organic and inorganic components with structure-property relations designed to yield new materials characterized by an array of novel behaviors and these materials would have real-world applications.

The field of nanochemistry crystallized in 1992 and gave birth to journals that publish nanochemistry with citation impact-factors matching or exceeding the flagship journal in their respective society and include: Small, Nano Letters, ACS Nano, Nature Nanotechnology, Nanoscale and the list continues to grow. Chemistry and nanotechnology were forever united, as evidenced by the astronomical growth of Nano Chemistry ISI citations since 1992, more than 360 million hits on Google, and the creation of numerous global initiatives in academic, industry, government, and defense institutions around research and education in nanochemistry. These initiatives would not likely have been possible without that foundational work carried out in the seventies, which subsequently inspired others to employ fundamental scientific principles and practices of nanochemistry to solve challenging real world problems in nanotechnology.

问：你认为你学术研究里的一个标志性工作是什么？

What would you say is one of the hallmarks of your research?

光子晶体等轻量化材料的前驱性发展。

The creative exploitation of the unique properties of regular arrangements of nanopores with dimensions that traverse nanometers to microns. For example, my research on periodic macroporous materials, which I aptly calls “light-scale” materials, a focus has been electrically, thermally, mechanically, and chemically tuned “colour from structure”. This revolutionary concept forms the basis of a new “photonic color” nanotechnology being developed by Opalux who are introducing three unique manifestations of this nanotechnology to the market.

P-Ink is a flexible, electronic paper-like material offering a full spectrum of electrically-tunable, reflective colours. Being bi-stable and power-efficient, it is one of three competitive technologies vying to add colour to black-and-white electronic book readers such as Kindle and Kobo. P-Nose is an artificial nose comprised of a simple, cost-effective pixilated array of surface-functionalized nanoporous materials that enable discrimination of different analytes, such as molecules comprising the unique identifiers of different bacteria. Think of the possibilities for medical diagnostics, and food and water quality-control! Elast-Ink is a touch-sensitive material that responds to mechanical pressure while offering exceptional resolution and customizability. It is poised to answer global demand for effective authentication-technology, serving, for example, the pharmaceutical and banknote-printing industries.

It is worth pointing out that the P-Ink photonic colour technology developed by Oplaux was recognized by the Technical Development Materials Award in the USA in 2011, which identifies the most innovative and significant technical achievement in the field of materials development. Opalux follows in the footsteps of many previous illustrious industry winners of this award in the US, Europe and Asia. In 2013, Opalux P-Ink Photonic Technology received the Global Innovation Award for its potential impact on the specialty colour displays industrial sector. Opalux Opal-Print Technology was runner-up in the 2013 Excellence in Tax Stamps Awards for best new innovation in anti-counterfeiting, anti-diversion, document security, brand protection and holography technologies. They have won many awards since then in recognition of their achievement of taking photonic color from the laboratory to the market place.

问：您觉得您的职业生涯中最科幻或者最有趣的发现是什么？

What do you feel is the most sci-fi or intriguing discoveries made during your career?

我是最早展示化学反应驱动 “纳米运动”的几位科学家之一。

I was among the first few scientists to demonstrate chemically-powered “nanolocomotion”. My work was based on chemical control of the motion of barcode nanorod motors, whose power is obtained from the decomposition of hydrogen peroxide into water and oxygen localized at the catalytic segment of the nanorod. The first experiments were aimed at nanorod rotors and motors and understanding the origin and control of their motion and speed. Subsequently I was the first to show how to make them flexible by integrating polymer hinges between the segments of the nanorod. These seminal papers inspired a veritable nanomotor industry. Activity in this field is now burgeoning around the world with envisioned nanomachine applications that include the removal of pollutants from water and as drug-carrying and delivery vehicles for targeted cancer therapy. In another burst of innovation, I discovered ultrathin inorganic nanowires which are characterized by unprecedented small < 2 nm diameters. These amazingly thin nanowires look, grow and behave like organic polymers. This work inspired a flurry of activity around the globe to explore the composition space and structure, properties, and functionality of these uniquely-thin one-dimensional constructs. This work raises an important question about how to expand and enrich the myriad applications enjoyed by organic polymers into the completely uncharted territory of ultrathin inorganic nanowires. The opportunities appear to be boundless!

问：您现在的研究兴趣是什么？

What do your current research interests look like?

纳米硅绿色化学，太阳能燃料。

Lately, I developed a passion for a greener kind of nanochemistry and figured out how to separate poly-dispersions of quantum-confined silicon nanocrystals into mono-dispersed colloidally-stable fractions with tailored organic surfaces. Incredibly, for the archetype semiconductor silicon, this feat was the first of its kind since the discovery of silicon nanocrystals more than thirty years ago. The brightly coloured visible to near infrared photoluminescence of these size-separated silicon nanocrystals enabled determination of their size-dependent absolute quantum yields. These photoluminescence quantum yields were found to be surprisingly high and as a result are targeted for a range of “green” nanotechnologies that include multicolour light-emitting diodes and biomedical diagnostics, therapeutics and imaging for detecting and targeting tumors. I believe green nanochemistry founded on benign nanocrystalline silicon will help alleviate the fear of cytotoxicity that currently pervades the use of heavy metal chalcogenide and pnictide nanomaterials currently favored for advanced materials and biomedical nanotechnologies. Recently I discovered the hydride capped versions of silicon nanocrystals are efficacious photocatalysts for the gas-phase, light-assisted hydrogenation of carbon dioxide to value-added chemicals and fuels, one of the highlights of the research of the solar fuels group that I established and spearheaded since its inception around a decade ago. I am excited that as a result of our pioneering work on carbon dioxide chemical and engineering solutions to climate change, the spin-off company Solistra has been founded recently to take our kind of solar fuels science and technology into the market place. 

问：作为一位教授，导师和教师的身份对您的职业生涯来说很重要吗？

As a professor, has being a mentor and teacher been important to you during your career?

我的职业生涯中特别重要且令我特别有成就感的一个方面是教育。首先也是最重要的，可以在学生的学术职业发展中最具挑战性的阶段对他们给予指导帮助，对我而言是一件非常荣誉，快乐和喜悦的事情。我所知道的知识都是伴随我的学生们一起学习获得的。这其中有50名学生在世界一流大学中获得了教职，其余的学生则是在工业界、政府、商业和法律等领域建立了出色和多样化的职业生涯。我为他们所取得的成就感到骄傲。

我与已毕业的学生Andre Arseault和Ludovico Cademartiri共同编写的教科书《纳米化学的概念》和《纳米化学:纳米材料的化学途径》，这两本书被全球公认为是向本科生和研究生介绍纳米化学的黄金标准参考书。近期，我和我的研究生Mireille Ghoussoub共同编写的《The Story of CO₂ — Big Ideas for a Small Molecule》将在2020年10月由多伦多大学出版社出版。这本书也表达了我对能源材料的发展和未来社会的可持续发展领域的研究与热情。

除此以外，我通过深入而有趣的演讲和在过去的十年里不间断的在“Advanced Science News”发表观点社论一百多篇，旨在让学术界，工业界，政府，媒体，商业，社会投资部门的科学家和工程师了解我们共同面对的紧迫问题。希望这些鼓舞人心，令人深思的观点可以为改善世界现况提供一些可行的方法。

问：和我们介绍下你的ArtNanoInnovations项目吧

Tell me about your project ArtNanoInnovations.

 Geoff和Todd(最左边前两位)

ArtNanoInnovations是我和艺术家Todd Siler在2011年共同成立的。在纳米科学和纳米技术的发展中，自然界给予了很多的创新灵感并帮助研究者解决全球性的挑战。ArtNano©的目的是用艺术去探索这些自然启发下的创新。我们通过多钟多样的艺术品来隐喻纳米科学和自然创造之间的联系。我和Todd的合作开始于2011年世界文化理事会会议。在这个会议上Todd的艺术工作和我的科学工作分别获得了达芬奇奖和爱因斯坦奖。

合作是一门艺术，而发展与创新过程也是一门科学。艺术和科学在这里完美相融，造就了我们的ArtNano©项目，在其中展示我们如何使用相同过程进行创造性学习并产生创新想法。我们的探索性工作考虑了纳米科学和纳米技术领域里众多实践创新的潜力，旨在帮助解决我们日前面对的很多紧迫的世界性问题。此外，我们的工作也探索了一些向全世界公众传达复杂信息的新方法。例如人类目前用各种策略和技术手段在原子和分子规模上巧妙地操纵物质，以产生前所未有的微小且多功能的结构和系统。ArtNano©项目提供了一些不同寻常的智慧，它们超越了心灵的障碍，超越了我们了解世界方式的差异。

备注：ArtNano© 里的©符号不只是代表版权（copyright）, 还代表创造力， 沟通，合作。此外，©还象征着能转化成无数种形式并在生活各处应用的“碳”元素。

问：您未来的计划是什么？

What are your future plans?

作为疫情中高危人群——老年人，由于目前还没有疫苗，我的未来计划也变得非常不确定。当然，在任何工作生活计划中，健康都是第一位的。最后还是取决于我和我的妻子Linda最后想在哪里工作、定居，可以是全职也可能是兼职的方式，可能是在加拿大，美国，英国或者比利时。我们一直致力于健康饮食和保持身体健康。我们也会继续在上述国家/地区和家人一起度过尽可能多的时光。

问：您有为您的生日安排什么特殊的计划吗？

Anything special planned for your birthday?

由于疫情，所有的庆祝都只能是在网上。如果可以，希望能和我以前的同事在网络上一起庆祝。

问：您希望未来能给世人留下什么？

What do you hope your legacy will be?

我认为从我学术生涯中提炼出来的基础研究成果，帮助定义和规范了纳米化学这一新的学科。纳米化学的科研成果也已经渗透到工业世界从产品，工艺到设备的各个角落，因此在我看来，这项成就建构了在研究前沿开展工作中的精髓。此外，纳米化学作为新兴学科，始终为许多科学相关工作中的进一步发展提供着不可或缺的驱动力，促进着科学，工业和经济的发展。换句话说，我相信我的工作首先展望了纳米材料的未来，并为通向维度不断缩小的新世界架起了一座桥梁。

T.S. Eliot 在Four Quartets中写道：“结束也是我的开始” 。Eliot深刻理解Aldous Huxley内心的想法“天才的秘诀是将孩子的精神带入老年”。Todd Siler说道：“Geoff的创造天赋源于他永恒的好奇心，创造力和求知欲”。

原文链接

https://www.advancedsciencenews.com/geoff-ozin-small-materials-with-a-big-impact/