Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

Photocatalytic CO(2) reduction using non-titanium metal oxides and sulfides.

Abstract: Titanium dioxide (TiO2 ) is by far the most widely used photocatalyst both for the degradation of pollutants and in the field of renewable energies for the production of solar fuels. However, TiO2 has strong limitations in CO2 reduction, particularly under visible light irradiation. The flat-band potential of electrons in the conduction band of TiO2 is lower than that required for CO2 reduction and, therefore, it seems appropriate to develop and validate materials other than TiO2 . In addition, the photoresponse of TiO2 requires photons of wavelengths in the UV range shorter than 380 nm and strategies to implement a visible-light photoresponse on TiO2 by doping have not been completely satisfactory particularly because of problems in reproducibility and stability of the materials. For these reasons, we focus in this Review on semiconductors other than TiO2 that show photocatalytic activity in CO2 reduction. Attention has been paid to the irradiation conditions to put the productivity data into context. The role of co-catalyst and heterojunctions to increase the efficiency of charge separation is also discussed. Our aim is to describe the state of the art in the field of photocatalytic CO2 reduction using materials other than TiO2 , trying to trigger further research in this area.

Solar Energy on Demand: A Review on High Temperature Thermochemical Heat Storage Systems and Materials.

Abstract: Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy storage systems to facilitate a round-the-clock electricity production at a global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as heat by sensible, latent, or thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible heat storage has been already incorporated to commercial CSP plants. However, because of its potentially higher energy storage density, thermochemical heat storage (TCS) systems emerge as an attractive alternative for the design of next-generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which can subsequently release the stored energy when needed through a reversible exothermic step. This review analyzes the status of this prominent energy storage technology, its major challenges, and future perspectives, covering in detail the numerous strategies proposed for the improvement of materials and thermochemical reactors. Thermodynamic calculations allow selecting high energy density systems, but experimental findings indicate that sufficiently rapid kinetics and long-term stability trough continuous cycles of chemical transformation are also necessary for practical implementation. In addition, selecting easy-to-handle materials with reduced cost and limited toxicity is crucial for large-scale deployment of this technology. In this work, the possible utilization of materials as diverse as metal hydrides, hydroxides, or carbonates for thermochemical storage is discussed. Furthermore, special attention is paid to the development of redox metal oxides, such as Co3O4/CoO, Mn2O3/Mn3O4, and perovskites of different compositions, as an auspicious new class of TCS materials due to the advantage of working with atmospheric air as reactant, avoiding the need of gas storage tanks. Current knowledge about the structural, morphological, and chemical modifications of these solids, either caused during redox transformations or induced wittingly as a way to improve their properties, is revised in detail. In addition, the design of new reactor concepts proposed for the most efficient use of TCS in concentrated solar facilities is also critically considered. Finally, strategies for the harmonic integration of these units in functioning solar power plants as well as the economic aspects are also briefly assessed.

Energy efficiency and thermal comfort in historic buildings: A review

Abstract: In recent years, energy efficiency and thermal comfort in historic buildings have become high-interest topics among scholars. Research has demonstrated that retrofitting buildings to current energy efficiency and thermal comfort standards is essential for improving sustainability and energy performance and for maintaining built heritage of historic structures. This study is an extensive overview of the literature surrounding this topic. This paper summarizes the different methods and techniques that have been used around the world to achieve performance refurbishments. Articles are organized based on the different building types used as case studies (residential, religious, academic and palace, museums, libraries and theaters, urban areas, and others). The results reveal that residential, religious and museum building types, especially from the last two centuries, have been most often used as case studies. Moreover, Europe, particularly Italy, is leading the research. The aim of this note is to demonstrate the feasibility of maintaining built heritage values of historic buildings while achieving significant improvements in their energy efficiency and thermal comfort.

Plant roots use a patterning mechanism to position lateral root branches toward available water

Abstract: The architecture of the branched root system of plants is a major determinant of vigor. Water availability is known to impact root physiology and growth; however, the spatial scale at which this stimulus influences root architecture is poorly understood. Here we reveal that differences in the availability of water across the circumferential axis of the root create spatial cues that determine the position of lateral root branches. We show that roots of several plant species can distinguish between a wet surface and air environments and that this also impacts the patterning of root hairs, anthocyanins, and aerenchyma in a phenomenon we describe as hydropatterning. This environmental response is distinct from a touch response and requires available water to induce lateral roots along a contacted surface. X-ray microscale computed tomography and 3D reconstruction of soil-grown root systems demonstrate that such responses also occur under physiologically relevant conditions. Using early-stage lateral root markers, we show that hydropatterning acts before the initiation stage and likely determines the circumferential position at which lateral root founder cells are specified. Hydropatterning is independent of endogenous abscisic acid signaling, distinguishing it from a classic water-stress response. Higher water availability induces the biosynthesis and transport of the lateral root-inductive signal auxin through local regulation of TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1 and PIN-FORMED 3, both of which are necessary for normal hydropatterning. Our work suggests that water availability is sensed and interpreted at the suborgan level and locally patterns a wide variety of developmental processes in the root.