To advance the progress of photoelectrolysis, various promising devices integrated with p- and n-type photocatalysts and dye sensitized photoelectrodes have been systematically studied. This review ...discusses, from theory to practice, an integration strategy for state-of-the-art dye sensitized solar cells (DSSCs) with potential p- and n-type photo-electrocatalysts or directly with dye sensitized photoanodes and cathodes for hydrogen and oxygen production through water splitting. Thorough insight into the theoretical approach which systematically drives the photoelectrolysis reaction directly or in a coupled mode, with diverse configurations of DSSCs and other photovoltaic (PV) cells, is crucial to understand the underlying fundamental concepts and elucidate trends in such reactions, and will serve as a guide to design new electrocatalysts and their integration with new PV devices, while simultaneously underlining major gaps that are required to address the challenges. Likewise, challenges, opportunities and frontiers in tandem and hybrid perovskite electrolysis processes are also discoursed in the present tutorial review. We illustrate our analysis by encompassing these integrated systems to photo-electrolysis, artificial photosynthesis such as CO
2
conversion into value-added chemical reduction-products, where advancements in new catalysts and solution-processed inexpensive PV devices can certainly enrich the overall performance of the renewable production of solar fuels, including solar driven carbonaceous fuels.
This review from theory to practice discusses the principles and designs of dye-sensitized semiconductor photoelectrodes for water splitting and electrolysis reactions.
Hybrid halide perovskite solar cells (PSCs) giving over 22 % power conversion efficiencies (PCEs) have attracted considerable attention. Although perovskite plays a significant role in the operation ...of PSCs, the fundamental theories associated with perovskites have not been resolved in spite of the increase in research. In this Minireview, we assess the current understanding, based on the first‐principles calculations, of structural and electronic properties, defects, ionic diffusion, and shift current for CH3NH3PbI3 perovskite, and the effect of ionic transport on the hysteresis of current–voltage curves in PSCs. The shift current connected to the possible presence of ferroelectricity is also discussed. The current state‐of‐the‐art and some open questions regarding PSCs are also highlighted, and the benefits, challenges, and potentials of perovskite for use in PSCs are stressed.
Better by calculation: First principles calculations of CH3NH3PbI3, including structural and electronic properties, defects, ionic diffusion, and shift current, can provide valuable support for further developing perovskite solar cells (PSCs).
Energy harvesting and storage devices, including lithium-ion batteries (LIBs), supercapacitors (SCs), nanogenerators (NGs), biofuel cells (BFCs), photodetectors (PDs), and solar cells, play a vital ...role in human daily life due to the possibility of replacing conventional energy from fossil fuels. However, these isolated devices only have limited performance and/or sole applicability, and cannot provide enough energy for application with long-term run and the ever-changing working positions. This suggests that it is urgent to develop the fine self-powered systems to meet the growing demand of energy for long-term use in different environment scenes. Developing integrated power pack, combining energy harvesting and storage, is an effective path to obtain a small size, light weight, high density and high reliability energy system. In this review, eight types of multifunctional integrated devices, such as LIB&SC, LIB&NG, BFC&NG, PD&BFC, SC&PD, SC&solar cells, NG&SC&solar cell, and LIB&solar cells, for energy harvesting and storage are reviewed in a broad sense, and a comprehensive summary of the recent development trends and highlights in the integrated device fields is given. Finally, the challenges and future outlooks for their successful commercialization are featured based on the recent advances and important findings.
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•Advanced energy-harvesting and storage technologies have been presented.•Typical energy harvesting and storage devices have been highlighted.•Recent advance in eight types of integrated devices have been reviewed.•Future development trend of integrated devices have been given.
Platinum (Pt)-free counter electrodes (CEs) are economical alternative components of dye-sensitized solar cells (DSSCs) that have attracted much interest and become the focus of research, with an ...increasingly large number of scientific papers published in the last two decades. The development of these CE materials was driven mainly by desires to overcome the disadvantages of Pt, as follows: high cost, scarcity, corrosion by the I
3
−
/I
−
redox couple electrolyte, and mismatch or non-effectivity in the I-free redox couple electrolyte. Although much more is now known about the principal physicochemical processes that occur during CE operation of the DSSC, the stability issues associated with CEs have not been matched by the exponential increase in CE research effort. This raises questions regarding the stability of the CEs whether the present research is sufficiently addressing the stability issues that limit DSSC performance. This review attempts to identify some of the key techniques that evaluate CE stability in DSSCs through a selective presentation of recent research highlights. Classical approaches could effectively assess the probability of using alternative Pt-free CE materials for commercial application, which offer strategies to overcome the current stability stalemate.
A comprehensive experimental evaluation using different techniques can provide a systematical assessment for CE stability of DSSCs from different angles.
The sharp increase of research passion in the new-generation solar cells in recent years has resulted in a new trend in combining multiple types of energy devices in a single device. In view of the ...enhanced and/or diversified function of integrated devices, as compared with conventional devices with limited performance or sole applicability, many integrated power packs have been widely developed by combining different devices, such as a silicon solar cell (SSC), Cu(In,Ga)(Sn,Se)
2
(CIGS), organic solar cell (OSC), dye-sensitized solar cell (DSSC), perovskite solar cell (PSC), lithium-ion battery (LIB), nanogenerator (NG), supercapacitor (SC), photoelectrosynthetic cell (PESC), and electrolysis cell (ELC), into one unit. In this Review, with a particular emphasis on their recent advances, we cover the integrated solar cell device research in a broad sense and provide an overview of state-of-the-art progress on the integrated solar cell devices based on DSSC and PSC, such as DSSC/LIB, DSSC/SC, DSSC/NG, DSSC/LIB/NG, PSC/OSC, PSC/CIGS, PSC/PSC, PSC/SSC, SSC/SC, PSC/SC, OSC/SC, DSSC/PESC, PSC/PESC, and PSC/ELC, for energy harvesting and storage that are significantly important for self-powering systems and portable/wearable electronics. Finally, the challenges and future outlooks in this promising photovoltaic (PV) field are featured on the basis of current development.
New-generation integrated devices based on dye-sensitized and perovskite solar cells for energy harvesting and storage are significantly important for self-powering systems and portable/wearable electronics.
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•Steel slags were firstly used as accelerants in the AD system.•Digestate with steel slag accelerants showed potential application as fertilizer.•Improved performance of AD due to the ...multi-elements released from steel slag.•Resource utilization and nonhazardous treatment of waste were achieved.
Accelerants can effectively enhance the performance of anaerobic digestion (AD) system. The effects of optimized steel slag as accelerant in the AD of cow manure and the fertility utilization of the digestate were investigated. Results show that all steel slags collected from different iron and steel companies (slag-1, slag-2, and slag-3) positively affect AD performance in terms of enhancing the biogas yield, methane yield, and chemical oxygen demand (COD) degradation rate. The cumulative biogas yield, methane yield, and COD degradation rate of slag-2 are 507.29 mL/g VS, 274.70 mL/g VS, and 58.62%, respectively. Thermal analysis reveals that the digestate with steel slag has excellent thermal stability and potential application as a component of nitrogen, phosphorus, and potassium organic compound fertilizers. The use of different steel slags as accelerants in the AD system provides a safe and economical avenue to realize the resource utilization and harmless treatment of waste resource.
The application of electrospun nanofibers in electronic devices is limited due to their poor adhesion to conductive substrates. To improve this, a seed layer (SD) is introduced on the FTO substrate ...before the deposition of the electrospun composite nanofibers. This facilitates the release of interfacial tensile stress during calcination and enhances the interfacial adhesion of the AZO nanofiber films with the FTO substrate. Dye-sensitized solar cells (DSSC) based on these AZO nanofiber photoelectrodes have been fabricated and investigated. An energy conversion efficiency (
η) of 0.54–0.55% has been obtained under irradiation of AM 1.5 simulated sunlight (100
mW/cm
2), indicating a massive improvement of
η in the AZO nanofiber film DSSCs after SD-treatment of the FTO substrate as compared to those with no treatment. The SD-treatment has been demonstrated to be a simple and facile method to solve the problem of poor adhesion between electrospun nanofibers and the conductive substrate.
The poor adhesion between electrospun nanofibers and substrate is improved by a simple and facile seed layer (SD) treatment. The energy conversion efficiency of AZO nanofiber-based DSSCs has been greatly increased by SD-treatment of the FTO substrate.
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► A simple and facile method (SD-treatment) has been demonstrated. ► The poor adhesion between electrospun nanofibers and substrate is improved by the SD-treatment. ► The
η of AZO nanofiber-based DSSCs has been greatly improved by SD-treatment of the FTO substrate.
Abstract
Producing electrolytes with high ionic conductivity has been a critical challenge in the progressive development of solid oxide fuel cells (SOFCs) for practical applications. The ...conventional methodology uses the ion doping method to develop electrolyte materials, e.g., samarium-doped ceria (SDC) and yttrium-stabilized zirconia (YSZ), but challenges remain. In the present work, we introduce a logical design of non-stoichiometric CeO
2-δ
based on non-doped ceria with a focus on the surface properties of the particles. The CeO
2−δ
reached an ionic conductivity of 0.1 S/cm and was used as the electrolyte in a fuel cell, resulting in a remarkable power output of 660 mW/cm
2
at 550 °C. Scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) clearly clarified that a surface buried layer on the order of a few nanometers was composed of Ce
3+
on ceria particles to form a CeO
2−δ
@CeO
2
core–shell heterostructure. The oxygen deficient layer on the surface provided ionic transport pathways. Simultaneously, band energy alignment is proposed to address the short circuiting issue. This work provides a simple and feasible methodology beyond common structural (bulk) doping to produce sufficient ionic conductivity. This work also demonstrates a new approach to progress from material fundamentals to an advanced low-temperature SOFC technology.
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•The low cost and accessible accelerants using in AD are designed and investigated.•Adding composited accelerants can improve biogas yield by 485.7–681.9 mL/g VS.•COD degradation rate ...(46.8–69.1%) are achieved in AD using developed accelerants.•The stabilized digestate with accelerants yield nutrient content of 4.95–5.56%.
To improve the methane yield and digestate utilization of anaerobic digestion (AD), low-cost composited accelerants consisting of urea (0.2–0.5%), bentonite (0.5–0.8%), active carbon (0.6–0.9%), and plant ash (0.01–0.3%) were designed and tested in batch experiments. Total biogas yield (485.7–681.9 mL/g VS) and methane content (63.0–66.6%) were remarkably enhanced in AD systems by adding accelerants compared to those of control group (361.9 mL/g VS, 59.4%). Composited accelerant addition led to the highest methane yield (454.1 mL/g VS), more than double that of control group. The TS, VS, and CODt removal rates (29.7–55.3%, 50.9–63.0%, and 46.8–69.1%) for AD with accelerants were much higher than control group (26.2%, 37.1%, and 39.6%). The improved digestate stability and enhanced fertilizer nutrient content (4.95–5.66%) confirmed that the digestate of AD systems with composited accelerants could safely serve as a potential component of bioorganic fertilizer. These findings open innovative avenues in composited accelerant development and application.
Mesoporous‐graphitic‐carbon‐supported HfO2 (HfO2‐MGC) nanohybrids were synthesized by using a soft‐template route. Characterization and a systematic investigation of the catalytic properties, ...stability, and catalytic mechanism were performed for HfO2‐MGC counter electrodes (CEs) in dye‐sensitized solar cells (DSSCs). The new HfO2‐MGC as a CE in DSSCs showed a surprisingly high efficiency of 7.75 % for the triiodide/iodide redox couple and 3.69 % for the disulfide/thiolate redox couple, greater than the Pt electrode in the corresponding electrolyte system, which opens up a possibility for its practical application.
Counter electrode culture: Dye‐sensitized solar cells (DSSCs) with a counter electrode (CE) of HfO2 supported on mesoporous graphitic carbon (MGC) exhibit high power conversion efficiencies for the I3−/I− and disulfide/thiolate redox couples, which are greater than those of DSSCs that use a Pt CE. Our calculations provide an understanding of these superior catalytic properties.
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