Recent Advances Towards Sustainable Materials and Processes for Energy Conversion and Storage

Abstract

Energy technologies must become a major green player in a competitive power-generation market, involving energy production in the form of electricity, chemical fuels, H2, etc. However, we must also consider other key aspects for the sustainability of the energy technologies. This includes the environmental impact of new materials, device production and recycling, while keeping a production cost milestone of > $1 per watt. To achieve this goal, we must continuously revise the preparation and type of new materials and concepts, fabrication methods, and device optimization production in concert with life-cycle analysis, resource availability, and environmental impacts. In this context, these special issues focus on the following fundamental aspects: i) the design and use of multifunctional hybrid systems as operational compounds/components in a myriad of energy technologies for solar fuels, air purification, thermoelectric, water splitting, CO2 reduction, NH3 production, photovoltaic technologies, electrochemical storage, etc. ii) the development of novel heterojunctions based on the combination of organic electroactive compounds with inorganic semiconductors allowing, for example, smart management of photons and carriers, and iii) the distinctive ecological features of bio-compounds for energy technologies, such as their unlimited low-cost production using bacteria and/or their fully recyclable nature. These contributions have highlighted our efforts towards material and design models of sustainability without losing device performance for energy applications. In particular, these special issues represent a joint effort between Advanced Energy Materials (AENM) and Advanced Sustainable Systems (ADSU) journals, including 15 reviews, and 14 original papers, covering the fields of i) photovoltaics focused on how biology, in general, and silk, cellulose, DNA-hybrids, polymers, hybrid carbon nanotubes, in particular, have recently impacted on solar-to-current conversion processes and device components towards, for example, smart buildings, ii) solar driven air purification materials, iii) solar energy conversion spanning from new engineered materials like porous polymers, nanoparticles, heterogeneous catalysts to new electrochemical/thermodynamic concepts, iv) batteries with emerging materials like biogenics, polymers, etc. and concepts about chemistry/recycling and sustainability, and v) new concepts in thermal management and thermoelectrics. As far as photovoltaics are concerned, Costa's group (AENM article number 2100520) has provided a comprehensive review about the third generation of photovoltaics and the efforts conducted to implement bio-derived materials/components to realize easy-to-do and low-cost recycling devices. This is rounded by i) two excellent reviews focused on dye-sensitized solar cells (DSSCs), namely, the implementation of poly(3,4-ethylenedioxythiophene) or PEDOT derivatives to design solid-state electrolytes as well as platinum-free counter electrodes (Bella's group; ADSU article number 2100025) and transparent DSSCs for smart buildings highlighting the challenges towards molecular design of low-energy absorbing dyes, electrolytes, and electrodes (Barolo's group; AENM article number 2101598), and ii) two excellent reviews discussing the processability and application of cellulose derivatives for light manipulation with respect to photonic crystals, substrates, electrolytes, etc. (Zollfrank's group; AENM article number 2003866) and silk fibers and their hybrid with ad-hoc mechanical and optical features for energy devices (Scheibel's group; AENM article number 2100519). Finally, this section is complemented with five original research papers of Hernandez-Sosa', Shalom', Vilatela's, Farinola', and Guerrero's labs. The former describes the first use of DNA derivative DNA- cetyltrimethylammonium (DNA-CTMA) as a universal ion-solvating component of the solid polymer electrolyte applied to electrochemical cells based on different emitters (ADSU article number 2000203). The second work (ADSU article number 2100005) describes how a new spray-coated deposition technique using a seeding layer of carbon nitride (CN) monomers leads to thick and homogeneous polymeric CN photoanodes with significantly enhance photocurrents. In this line, Vilatela's lab (ADSU article number 2000265) reports the use of carbon nanotube fiber fabric as a substrate to create a thin CN layer that leads to a hybrid material merging high electrical conductivity, mechanical features, and enhanced electrochemical surface area. Farinola's lab (ADSU article number 2000303) explains how to create innovative soft nanoparticles embedding Rhodobacter sphaeroides Reaction Center in polydopamine that are capable of converting sun-light into electricity with a similar performance to that in solution. Finally, Guerrero's lab (ADSU article number 2100120) clarifies the main limitation in perovskite solar cells to offer high power conversion under diffuse or low illumination conditions, reaching efficiency values of 32% by doping the SO2 electron transport layer with Pb. Following up on the use of sun energy as driving force, this special issue also covers the recent advances in solar fuels and solar purification processes. The recent achievements in solar fuels are summarized in 4 reviews and 4 original research papers. In short, two reviews are focused on one of the most ground-breaking topics in solar fuels, the replacement of inorganic semiconductors by photoactive organic systems. Thus, de la Peña O'Shea's group (AENM article number 2101530) have described the last advances in the use of conjugated organic polymers (CPPs) or covalent organic frameworks (COFs) and their hybrids as photocatalyst or photoelectrodes in a wide range of solar driven technologies such as: H2 production, CO2 photoreduction; O2 evolution and organic photovoltaics. In addition, Nishide's group (AENM article number 2003724) provides an interesting revision describing the fundamentals of using organic π-conjugated polymers as photocathode for visible light-enhanced hydrogen and hydrogen peroxide production from water. Following with solar fuels production, two works are also focused on the photocatalytic H2 production. Titirici's group (AENM article number 2101180) provides a comprehensive critical review about progress in the development of photo- and electrochemical processes using biomass derived materials as effective hydrogen carrier, including a techno-economic assessment and life cycle analysis. Finally, Huirache's group (ADSU article number 2100133) describes the effect of using a mesostructured silica framework (SBA-15) as effective support for inorganic semiconductors improving the photocatalytic H2 production. This section is complemented with three works dedicated to solar driven electrochemical technologies. Fontcave's group (AENM article number 2002652) revises the integration of photovoltaics cells on photo- electrochemical and electrochemical summarizing the pros and cons of both strategies in solar-driven CO2 reduction. Barreca's group (ADSU article number 2000177) has presented a study based on the use of Earth-abundant and eco-friendly manganese oxides, which are promising platforms for the oxygen evolution reaction (OER). Following with OER, Escudero-Escribano's (ADSU article number 2000284) group proposes iridium decorated tungsten sulphide as highly actives and stable anodes for O2 evolution. Including in solar fuel section but based on solar concertation technologies Alvarez's groups (ADSU article number 2100029) shows the influence on the activity and selectivity of Ni loading in a La-doped ceria catalyst for CO2 reduction by reverse water gas shift reaction. In a related field, Fu's group (ADSU article number 2100027) provides an excellent review about photochemical degradation of organic matter in the atmosphere and how it strongly impacts the delicate atmospheric harmony that ultimately affects the climate and our health. More specifically, Fresno's group (ADSU article number 2100071) describes the design of efficient Au/TiO2 nanocolumn electrodes combining photo-induced self-cleaning and hydrophobic features. In this line, Kusic's group (ADSU article number 2100119) also describes how the fabrication of a multilayered TiO2/Fe2O3 electrodes are superior to degrade amoxicillin compared to other traditional electrodes regardless of the type of water components. Finally, Gómez-Ruiz's lab (ADSU article number 2000298) provides an interesting work in which the co-doping of TiO2 with Cu and F atoms leads to efficiency catalyst to eliminate ciprofloxacin and naproxen in short periods of time. Concerning batteries, Schubert', Slabon', Inganäs', and Gerbaldi's groups have provided five reviews that cover the most important aspect concerning the sustainable future of the battery field. In short, Schubert’ group (AENM article number 2001984) revises the use of polymers as active materials to storage energy, membranes, and binders in lithium cells, redox-flow systems, and polymeric thin-film batteries. Slabon's group (AENM article number 2003456) focuses on the chemistry and recycling of Li-ion batteries that includes the use of toxic elements, the in-situ formation of toxic compounds, waste production and down-cycling issues. In this line, Inganäs’ group (AENM article number 2003713) describes how to design batteries using biogenic materials derived from plants if electrochemistry is applied to make them functional for this field, while Gerbaldi's group (AENM article number 2100785) focuses on the fabrication and performance of batteries based on Na, K, Ca, Mg, Zn, and Al monovalent and multivalent metal anodes. Finally, the field of thermoelectrics was nicely reviewed by experts in this field like Martín-González’ and Xu's labs. In detail, Martín-González’ lab (ADSU article number 2100095) offers a comprehensive review about the thermoelectric technology and how to address the development of eco-friendly and abundant inorganic materials to realize high performing devices. In this context, Xu's group (ADSU article number 2000202) describes a new solar driven interfacial water evaporation concept to efficiently produce localized heat based on an electrostatic flocking approach. All-in-all, this special issue illustrates the excellence past and current research of leading scientists shaping sustainability of energy technologies covering conversion and storage. We are heartily grateful to all the authors, the referees, the editor (Dr. Till von Graberg), and the whole team at Wiley-VCH for their efforts to carry this special issue forward. The authors declare no conflict of interest. Víctor A. de la Peña O'Shea received his Ph.D. in Physical-Chemistry (2003) from the Universidad Autonoma de Madrid and the Catalysis and Petrochemistry Institute (Spain). After his Ph.D., he spent three years at Universidad de Barcelona, where he got the MSc in Physic. In 2008, he moved to IMDEA Energy, where he is the Head of the Photoactivated processes Unit. He has co-authored more 140 publications/patents/books. He has coordinated more than 20 research projects, including an ERC-CoG. His research group is focused in the design and development of novel heterogeneous catalysts and reactors applied to sustainable energy and environmental technologies. Rubén D. Costa received his Ph.D. from the U. Valencia (Spain) in 2010 and was Humboldt post-doc at the U. Nürnberg-Erlangen (Germany) from 2011–2013. In 2014 he started the Hybrid Optoelectronic Materials and Devices Lab as Liebig group leader (2014-2017). In 2017, he moved his group to IMDEA Materials (Spain) and expanded to U. Waseda (Tokyo) as associate Professor in 2018. Since 2020 he leads the chair for Biogenic Functional Materials focused on energy applications at the Technical University of Munich. He has reported >150 scientific publications/books/patents and has been recipient of >35 awards/mentions/fellowships.