Final Report Summary - MINE (Developing New Strategies for the Production of Viable Hybrid Nanocrystals with Applicability in Energy Conversion and (Photo)catalysis.)
In the recent years there have been tremendous developments in the synthetic control of inorganic nanocrystals (NCs) which allow tailoring their dimensional regime (morphology, composition and structure) and their physicochemical properties. These properties, alongside with the ability to cheaply produce NCs in fairly large amounts lead to their potential applicability in diverse fields, especially in energy harvesting and catalysis.
Remarkably, this applicability can be even increased by designing NCs with a finer morphological control of their properties. In this context, MINE has aboard the most problematic points related to the production of advanced complex materials by integrating the synthesis, the structural characterization and the study of NC’s properties. The research activities included four individual objectives: i) the design and development of synthetic protocols for the production of advanced complex NCs, ii) the study of their structure-activity relationships, iii) the determination of their applicability in model systems and real scenarios and iv) the study of their long-term use in terms of safety, sustainability and feasibility.
The first objective involved the exploration of new tools and strategies to manipulate the synthesis of inorganic NCs, particularly the study of nucleation and growth kinetic processes. This study was initiated at the very beginning of the project and has allowed us to develop new synthetic strategies and re-design some already reported providing new routes for reproducible and scalable synthesis of noble metal NCs. Especially remarkable is the unprecedented morphological control achieved for noble metals, controlling NCs size with nanometric precision in the size range of 3 to 200 nm and producing Ag shapes with an unprecedented control of their morphology. Getting advantage from this experience, we successfully extended our study to the production of oxides and semiconductor NCs.
After establishing these synthetic principles, we shifted our efforts to the development of synthetic protocols for the production of more complex and sophisticated materials, in terms of morphology, composition, and therefore properties. These studies, involving the understanding of the chemistry at the interface between the liquid and the solid phases, allowed us to control the parameters which affect the hetero-epitaxial growth of NCs. Besides, we also focused our efforts in the fine control the inner morphology (solid or void) of the NCs. This strategy allowed us to produce NCs with a fine control of its porosity of the NCs and tune important structural, morphological and compositional parameters such as the crystal facets exposed and the degree of alloy with other metals.
The second objective addressed the study of the structure-activity relationships of the NCs previously produced. It included i) the extensive characterization of the NCs (morphology, structure and composition), ii) the determination of their physicochemical properties, iii) the correlation of their final properties with the synthetic conditions used, and iv) the study of their chemical reactivity. As a result, we have obtained outstanding results in the morphological and structural (size, shape, composition and surface chemistry) dependences of physicochemical properties of NCs. We also studied the reactivity of the NCs, particularly which interactions phenomena at the nanoscale could affect the final structure of the NCs. From the study of these processes we redesigned synthetic protocols of NCs. Besides, modeling tools were used to correlate the optical properties of the NCs after their exposition to complex scenarios. In particular, we studied how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution.
The third objective has involved the evaluation of the applicability of obtained NCs as (photo)catalysts both in real systems and model scenario. The catalytic properties of the NCs were measured by employing the reductive degradation of organic dyes (p-nitrophenol, Rhodamine B, methylene blue and methylene orange) by NaBH4 as a model reactions. We determined the surface catalytic activity of as-synthesized NCs and hybrid structures based on NCs showing how the precise morphological control of the surface of inorganic NCs is critical for the development of highly active and low-cost materials.
Finally, the fourth objective has been the study of the NCs from a holistic perspective, in the framework of NCs full life cycle, i.e. from the synthesis of the material to its final application. These studies have allow us re-design synthetic protocols and develop strategies to evaluate the safe and rational use of nanomaterials following safe by design principles.
The research progress made and the results obtained represent a significant advance beyond the state of the art in the field, allowing to combine a highly evolved synthetic control with a fundamental understanding of the size- and shape-dependent properties at the nanoscale. This has provided a “tool-box” of materials and morphologies available for researchers in the field to better understand the precise behavior of the solid state at the nanoscale.
Besides, on the greater perspective of scientific, technological and social impact, MINE has represented an excellent opportunity for joining, coordinating and advancing pioneering research efforts enabling collaborative internalitional collaborations and technological transfer activities. In parallel, this project has represented a strong support to attain my professional maturity and independence. In this regard, my progress of reintegration to the Spanish scientific system has been extremely positive, receiving in April 2013 a tenure-track "Ramón y Cajal" Fellowship (MICINN, Spanish Government), ranked first in the area of Engineering and Technology, Materials Science.
Remarkably, this applicability can be even increased by designing NCs with a finer morphological control of their properties. In this context, MINE has aboard the most problematic points related to the production of advanced complex materials by integrating the synthesis, the structural characterization and the study of NC’s properties. The research activities included four individual objectives: i) the design and development of synthetic protocols for the production of advanced complex NCs, ii) the study of their structure-activity relationships, iii) the determination of their applicability in model systems and real scenarios and iv) the study of their long-term use in terms of safety, sustainability and feasibility.
The first objective involved the exploration of new tools and strategies to manipulate the synthesis of inorganic NCs, particularly the study of nucleation and growth kinetic processes. This study was initiated at the very beginning of the project and has allowed us to develop new synthetic strategies and re-design some already reported providing new routes for reproducible and scalable synthesis of noble metal NCs. Especially remarkable is the unprecedented morphological control achieved for noble metals, controlling NCs size with nanometric precision in the size range of 3 to 200 nm and producing Ag shapes with an unprecedented control of their morphology. Getting advantage from this experience, we successfully extended our study to the production of oxides and semiconductor NCs.
After establishing these synthetic principles, we shifted our efforts to the development of synthetic protocols for the production of more complex and sophisticated materials, in terms of morphology, composition, and therefore properties. These studies, involving the understanding of the chemistry at the interface between the liquid and the solid phases, allowed us to control the parameters which affect the hetero-epitaxial growth of NCs. Besides, we also focused our efforts in the fine control the inner morphology (solid or void) of the NCs. This strategy allowed us to produce NCs with a fine control of its porosity of the NCs and tune important structural, morphological and compositional parameters such as the crystal facets exposed and the degree of alloy with other metals.
The second objective addressed the study of the structure-activity relationships of the NCs previously produced. It included i) the extensive characterization of the NCs (morphology, structure and composition), ii) the determination of their physicochemical properties, iii) the correlation of their final properties with the synthetic conditions used, and iv) the study of their chemical reactivity. As a result, we have obtained outstanding results in the morphological and structural (size, shape, composition and surface chemistry) dependences of physicochemical properties of NCs. We also studied the reactivity of the NCs, particularly which interactions phenomena at the nanoscale could affect the final structure of the NCs. From the study of these processes we redesigned synthetic protocols of NCs. Besides, modeling tools were used to correlate the optical properties of the NCs after their exposition to complex scenarios. In particular, we studied how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution.
The third objective has involved the evaluation of the applicability of obtained NCs as (photo)catalysts both in real systems and model scenario. The catalytic properties of the NCs were measured by employing the reductive degradation of organic dyes (p-nitrophenol, Rhodamine B, methylene blue and methylene orange) by NaBH4 as a model reactions. We determined the surface catalytic activity of as-synthesized NCs and hybrid structures based on NCs showing how the precise morphological control of the surface of inorganic NCs is critical for the development of highly active and low-cost materials.
Finally, the fourth objective has been the study of the NCs from a holistic perspective, in the framework of NCs full life cycle, i.e. from the synthesis of the material to its final application. These studies have allow us re-design synthetic protocols and develop strategies to evaluate the safe and rational use of nanomaterials following safe by design principles.
The research progress made and the results obtained represent a significant advance beyond the state of the art in the field, allowing to combine a highly evolved synthetic control with a fundamental understanding of the size- and shape-dependent properties at the nanoscale. This has provided a “tool-box” of materials and morphologies available for researchers in the field to better understand the precise behavior of the solid state at the nanoscale.
Besides, on the greater perspective of scientific, technological and social impact, MINE has represented an excellent opportunity for joining, coordinating and advancing pioneering research efforts enabling collaborative internalitional collaborations and technological transfer activities. In parallel, this project has represented a strong support to attain my professional maturity and independence. In this regard, my progress of reintegration to the Spanish scientific system has been extremely positive, receiving in April 2013 a tenure-track "Ramón y Cajal" Fellowship (MICINN, Spanish Government), ranked first in the area of Engineering and Technology, Materials Science.