Direct Carbon Solid Oxide Fuel Cells Research Articles

Completely sealed direct carbon solid oxide fuel cell with in situ steam-carbon gasification reaction

Direct carbon solid oxide fuel cells (DC-SOFCs) offer the potential for clean and efficient conversion of chemical energy in carbon fuels into electricity. However, the reverse Boudouard gasification of carbon requires a high operating temperature (≥800 °C), which hinders the development of DC-SOFCs. We present a completely sealed DC-SOFC with in situ steam-carbon gasification. The cells have a symmetrical cell structure (Ag–Ce0.8Gd0.2O1.9/La0.9Sr0.1Ga0.8Mg0.2O3−δ/Ag–Ce0.8Gd0.2O1.9) and are loaded with K-loaded activated carbon fuel. Ca(OH)2 and Li4SiO4 are loaded into the anode chamber as the steam feedstock and CO2 sorbent, respectively. Completely sealed DC-SOFCs with Ca(OH)2–C of 0 %, 5 %, 10 %, 15 %, and 20 % have been tested at 700 °C. Compared with a cell with a conventional structure and a completely sealed cell without Ca(OH)2 loading, the electrochemical performances of all the completely sealed cells with Ca(OH)2 loading are significantly enhanced. The cell with Ca(OH)2 to C of 15 % obtained the highest maximum power density of 75 mW cm−2, which is approximately two-fold that of the conventional DC-SOFC. The mechanism for improving the performance of the cell is the introduction of steam. This study offers a new method to develop high-performance DC-SOFCs and reduce their operating temperatures.

Simultaneous electrochemical reduction of water and oxidation of carbon in a solid oxide cell for separately producing hydrogen and carbon monoxide

Hydrogen can be produced from reduction of water at the cathode of a solid oxide electrolysis cell (SOEC) and electricity and CO gas can be co-generated from the oxidation of carbon at the anode of a direct carbon solid oxide fuel cell (DC-SOFC). In the present work, a solid oxide cell (SOC) combining the cathode reaction of the SOEC and the anode reaction of the DC-SOFC is proposed, prepared, and investigated. It is demonstrated that hydrogen and CO can be separately produced from the cathode and anode through simultaneous reduction of water and oxidation of carbon in such a H2O-C SOC. Resistances from electrode polarizations are analyzed through measuring current-voltage characteristics, overpotentials, and AC impedances of the cell. The advantage of the H2O-C SOC over two separately operated SOEC and DC-SOFC is verified by the resistance analysis. An electrolyte-supported H2O-C SOC, with a cermet of silver and gadolinium-doped ceria (Ag-GDC) as the symmetrical electrode material and a steam concentration of 50 % at the cathode, gives an operating current density of 0.67 A cm-2 at the thermal neutral voltage (0.7 V). It stably operates at 0.2 A cm-2 under an applied voltage of only 0.16 V, producing pure hydrogen from the cathode and CO with a concentration of 88 % from the anode. The performance is significantly improved by using an anode-supported H2O-C SOC which gives an operating current density of 2.27 A cm-2 at the thermal neutral voltage.

Investigating the Effects of the Physicochemical Properties of Cellulose-Derived Biocarbon on Direct Carbon Solid Oxide Fuel Cell Performance.

This paper presents a study of the characteristic effects of the physicochemical properties of microcrystalline cellulose and a series of biocarbon samples produced from this raw material through thermal conversion at temperatures ranging from 200 °C to 850 °C. Structural studies revealed that the biocarbon samples produced from cellulose had a relatively low degree of graphitization of the carbon and an isometric shape of the carbon particles. Based on thermal investigations using the differential thermal analysis/differential scanning calorimeter method, obtaining fully formed biocarbon samples from cellulose feedstock was possible at about 400 °C. The highest direct carbon solid oxide fuel cell (DC-SOFC) performance was found for biochar samples obtained via thermal treatment at 400-600 °C. The pyrolytic gases from cellulose decomposition had a considerable impact on the achieved current density and power density of the DC-SOFCs supplied by pure cellulose samples or biochars derived from cellulose feedstock at a lower temperature range of 200-400 °C. For the DC-SOFCs supplied by biochars synthesised at higher temperatures of 600-850 °C, the "shuttle delivery mechanism" had a substantial effect. The impact of the carbon oxide concentration in the anode or carbon bed was important for the performance of the DC-SOFCs. Carbon oxide oxidised at the anode to form carbon dioxide, which interacted with the carbon bed to form more carbon oxide. The application of biochar obtained from cellulose alone without an additional catalyst led to moderate electrochemical power output from the DC-SOFCs. The results show that catalysts for the reverse Boudouard reactions occurring in a biocarbon bed are critical to ensuring high performance and stable operation under electrical load, which is crucial for DC-SOFC development.

Alternative green application areas for olive pomace catalytic pyrolysis biochar obtained via marble sludge catalyst

Evaluating industrial wastes in the system with minimum preprocessing and generation economically valuable products from them have critical importance. In this regard, especially cheap, wieldy, and readily available catalysts have been researched to increase variety of useful products in pyrolysis systems, to reduce process time, and to increase quality and diversity of products. Therefore, in this study, marble sludge (named K1) was evaluated as catalyst at different dosages (10%, 20%, 30%, 50%) and pyrolysis temperatures (300, 500, 700 °C) in olive pomace (OP) pyrolysis and; the potential green applications of produced new biochars at new usage areas with different purposes based on characteristics were investigated. ANOVA test results showed that temperature and catalysts ratio had significant effect on pyrolysis product yields since significance value for K1 and temperature was lower than 0.05 for pyrolysis products. OP-K1 biochars had alkaline properties and high earth metal quantities. Moreover, increment in K1 ratio and temperature resulted in decrement of the biochar surface acidity. Therefore, it can be indicated that these biochars can have a potential usage for anaerobic digestion processes, lithium-ion batteries, and direct carbon solid oxide fuel cell (DC-SOFC) but further electrochemical property test should be performed. Moreover, produced biochars can be alternative fuels in some processes instead of coal since they have low S content and high heat values. Consequently, it is foreseen that produced biochars will have an important place in the development of potential usage areas with a new and environmentally friendly approach in different areas apart from the conventional uses of catalytic pyrolysis chars.Graphical abstract

Innovative application of tomato straw biochar in direct carbon solid oxide fuel cells for power generation

Direct carbon solid oxide fuel cells (DC-SOFCs) demonstrate significant promise in clean energy conversion technology due to their direct utilization of solid carbon, high-temperature operation, and fuel flexibility. Exploring biomass as a fuel for DC-SOFCs is particularly intriguing within this context. Here, we successfully developed the biochar derived from tomato straw and conducted a comprehensive physicochemical characterization to investigate its feasibility and advantages for DC-SOFCs. Electrochemical results revealed that DC-SOFC powered by tomato straw biochar achieved an impressive output of 219 mW cm−2 at 850 °C, surpassing the cell output of 187 mW cm−2 operating on commercial activated carbon. Furthermore, the single cell demonstrated a higher discharge plateau and a longer lifetime of 26.5 h under 50 mA at 850 °C. Consequently, fuel utilization was calculated to be up to 29.7%, which was also superior to that of activated carbon-fueled DC-SOFC, further validating the effectiveness of tomato straw biochar in improving DC-SOFC performance. These outstanding performances were primarily attributed to the unique porous microstructure, naturally existing metal elements, high disorder and large specific surface area of the biochar, which effectively promoted the reverse Boudouard reaction to produce a substantial amount of CO for anode reaction, thus enhancing the DC-SOFC performance and efficiency. These findings underscore the enormous application potential of tomato straw biochar for DC-SOFCs, providing strong support for advancing clean energy technology and achieving carbon neutrality goals.

Development of a tubular direct carbon solid oxide fuel cell stack based on lanthanum gallate electrolyte

The direct carbon solid oxide fuel cell (DC-SOFC) is a new-type energy conversion device that converts chemical energy stored in solid carbon into electricity efficiently with environmental benignity and low cost for abundant carbon resources, which reveals upward impetus recently. To accelerate the practical application of DC-SOFC, here, we report a high-performance La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) electrolyte-supported tubular DC-SOFC stack for portable applications, in which Ag– Ce0.8Gd0.2O1.9 (Ag-GDC) is used as symmetrical electrodes and camellia oleifera shell char as fuel. The performance of the 3-cell-stack stands out, with an open circuit voltage (OCV) of 3.18 V, an output power of 2.65 W, and a maximum volumetric power density of 605 mW cm−3 at 800 °C. In addition, the stack can survive for 5.82 and 1.12 h under the constant discharging currents of 200 and 800 mA, respectively, exhibiting discharge capacities of 3492 and 2688 mA h. Furthermore, adopting the external anode design can sextuple the fuel load and lead to remarkably improved output performance, discharge time, and discharge capacity of the stack (3.71 W, 9.2 h, 22080 mA h). The above results indicate that LSGM electrolyte-supported tubular DC-SOFC stacks show great potential for developing into high-performing, efficient, and environmentally friendly portable power sources for distributed applications.

New insights into single-step fabrication of finger-like anode/electrolyte for high-performance direct carbon solid oxide fuel cells: Experimental and simulation studies

Cell preparation techniques and design parameters have significant impacts on the electrochemical performance of direct carbon solid oxide fuel cells (DC-SOFCs). In this work, a finger-like nickel-based anode/electrolyte has been successfully fabricated in a single step via the tape-casting combined phase-inversion and co-sintering technique, which simplified the preparation process and reduced the fabrication cost. The finger-like anode/electrolyte exhibited identical microstructure and exceptional adhesion, ensuring the absence of any cracks during the co-sintering process. As a result, the corresponding single cell delivered a very competitive output of 436 mW cm−2 at 850 °C using activated carbon as fuel. Moreover, it operated stably for 20.1 h under 100 mA with a high fuel utilization of 22.5% at 850 °C. Model verification was also performed by comparative analysis of the effects of the finger-like pore length, anode thickness, cathode thickness, and electrolyte thickness on the cell performance using numerical simulation, which generated the resultant two-dimensional distributions of CO molar concentration, current density, O2 molar concentration, and temperature as well as the power output of the cell. Simulation results verified the experimental findings that DC-SOFC performance was enhanced with increases in the finger-like pore length and cathode thickness, and with decreases in the anode and electrolyte thicknesses. This work provides valuable insights into further optimizing the cell design and manufacturing process, paving the way for the development of high-performance DC-SOFCs.

Simulation-guided design of a finger-like nickel-based anode for enhanced performance of direct carbon solid oxide fuel cells

Direct carbon solid oxide fuel cells (DC-SOFCs) can convert solid carbon directly to electricity via electrochemical oxidation and require less investment compared to other liquid or gas-fed fuel cells. Anode characteristic is one of the important factors in achieving efficient and stable operation of DC-SOFCs. In this work, we have successfully designed and developed 2D multi-physics field models for DC-SOFCs with finger-like nickel-based anode (Cell-A) and traditional nickel-based anode (Cell-B), respectively. Simulation results revealed that the cell performance was significantly enhanced with increases in the anode porosity and decreases in the distance of carbon fuel to porous anode. More importantly, the anode featuring a finger-like pore structure assumed a pivotal role in cell performance. Specifically, Cell-A exhibited higher electrochemical performance compared to Cell-B due to the lower resistance for gas transport and more abundant amount of three-phase boundaries for electrochemical reactions. Experimental results verified the simulation findings by making and operating these two DC-SOFCs. The fabricated Cell-A with finger-like anode delivered higher power output of 858 and 371 mW cm−2 at 850 °C when fueled with hydrogen and activated carbon, respectively, relative to Cell-B with traditional anode. The beneficial characteristic of finger-like anode was further demonstrated by the ability of Cell-A to retain stable operation for 14.1 h at 100 mA with the fuel utilization of 15.8% at 850 °C. This study provides important guidance for the design and improvement of DC-SOFCs, and promotes the sustainable utilization of carbon resources.

Experimental and numerical study of micro-tubular direct carbon solid oxide fuel cell fueled by the oilseed rape straw-derived biochar

Direct carbon solid oxide fuel cells (DC-SOFCs) can directly utilize solid carbon to generate electricity. However, the fuel cells' carbon fuel sources and configuration may significantly affect their electrochemical performance. In this work, we systematically investigate the electrochemical performance of the micro-tubular DC-SOFC (MT-DC-SOFC) using the oilseed rape straw (ORS)-derived biochar by experimental and simulation numerical studies. For the first time, the ORS biochar is introduced in DC-SOFCs to improve electrochemical performance. As expected, the single cell delivers the best output of 222 mW cm−2 at 850 °C, which is comparable to that of hydrogen-fueled SOFC. Besides, the MT-DC-SOFC exhibits a long operating lifetime of 11.9 h under a 100 mA constant current with the fuel utilization of 23.8% at 850 °C, verifying that the ORS biochar is an excellent carbon fuel for DC-SOFCs. Moreover, multi-physical field modeling is applied to evaluate the mechanism of the MT-DC-SOFC. The simulation results verify the experimental findings that the cell performance is significantly affected by the electrolyte with finger-like pores, carbon fuel location and area, and electrode thickness. This work presents a novel green strategy for developing high-performance MT-DC-SOFCs that can efficiently utilize the ORS biochar and other biomass.

Anthracite pretreatment for high-performance direct carbon solid oxide fuel cell — A green pathway for power generation

Coal-fueled direct carbon solid oxide fuel cell (DC-SOFC) is a very attractive electrochemical conversion device. However, coal contains a certain amount of ash, such as Al, Si, S, etc., which are toxicants for SOFC components. To solve the above problem, anthracite is pyrolyzed at 600 °C to obtain semi-coking coal results in better cell performance. The results show that the higher carbon gasification oxidation activity of semi-coking coal is due to the higher amount of fixed carbon and catalyst. Therefore, more fuel gas (CO) is available in the anode chamber for the Boudouard reaction. Also, the electrochemical performance of both coals as DC-SOFC fuel was compared using La0·4Sr0·6Co0·2Fe0·7Nb0·1O3-δ (LSCFN) as anode. The maximum power density (MPD) of the DC-SOFC with semi-coking coal is 596 mW cm−2 at 850 °C, much higher than that of the SOFC using anthracite (396 mW cm−2) as the fuel. Furthermore, at the same fuel content, the cell fueled with semi-coking coal has a longer discharge time (30 h), which shows a better stability.

Layered perovskites with exsolved Co-Fe nanoalloy as highly active and stable anodes for direct carbon solid oxide fuel cells

The performance and stability of direct carbon solid oxide fuel cells (DCSOFCs) are severely affected by the electrocatalytic activity of their anode materials. In this work, a cobalt doped layered perovskite, (PrBa)0.95Fe1.8−xCoxNb0.2O5+δ (PBFCoxN, x = 0, 0.1, 0.2, 0.3), is investigated as the anode material for a DCSOFC. Co3Fe7 alloy particles are exsolved on the perovskite substrate under the reduction of carbon, which improves CO chemisorption and electrochemical oxidation. This enhances the electrochemical performance of the anode. The electrolyte-supported cell with a (PrBa)0.95Fe1.6Co0.2Nb0.2O5+δ (PBFCo0.2N) anode achieves a peak power density of 525.6 mW cm−2 at 800 °C, fueled by activated carbon. The performance of this anode material is comparable to or exceeds that of previously reported anodes, indicating that the PBFCo0.2N anode is a promising option for DCSOFCs.

Sr2Fe1.5Mo0.4Ti0.1O6-δ perovskite anode for high-efficiency coal utilization in direct carbon solid oxide fuel cells

Efficient and direct utilization of coal-based fuels is the developmental direction of direct carbon solid oxide fuel cells (DCSOFCs), but their performance is hindered by poor catalytic activity and contaminant poisoning of anode materials. Herein, a Ti-doped double perovskite oxide Sr2Fe1.5Mo0.4Ti0.1O6-δ (SFMT) was developed as the coal-based DCSOFC anode to improve its catalytic activity and resistance to sulfur poisoning. X-ray photoelectron spectroscopy confirms that SFMT shows abundant oxygen vacancy concentration under reducing atmosphere. The as-fabricated DCSOFC with the SFMT anode delivers a maximum power density of 506.5 mW cm−2 at 800 °C when using bituminous coal as the fuel. Electrochemical impedance spectroscopy reveals that Ti doping can effectively promote electrochemical processes on the anode side. Both thermogravimetric analysis and CO temperature-programmed desorption demonstrate that the performance improvement of SFMT is ascribed to its promoted catalytic activity in coal gasification and its increased CO adsorption capacity. The operational period of this coal-based DCSOFC increases from 2 to 10 h after Ti doping, which can be explained by the enhanced structural stability of SFMT under a sulfur-containing environment. Our work may provide some new insight on the design of high-activity anode materials and the understanding of anode reaction mechanisms for coal-based DCSOFCs.

Fe-Based Layered Double Perovskite Anode with in Situ Exsolved Nanoparticles for Direct Carbon Solid Oxide Fuel Cells

Direct carbon solid oxide fuel cells (DC-SOFCs), which can efficiently convert chemical energy of carbonaceous fuels into electricity, have recently gained much research attention as they offer an effective way to address future economic and environmental challenges. Herein, B-site Ti-substituted (PrBa)0.95Fe2–xTixO6−δ (PBFTx, x = 0–0.3) materials are synthesized via a sol–gel combustion method and evaluated as anode materials for DC-SOFCs. Ti doping enhances the phase structure stability of the material under a reducing atmosphere. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses demonstrate the exsolution of metallic Fe nanoparticles on the surface of the PBFTx perovskite lattice after the materials are treated under a reducing atmosphere, which can improve the catalytic performance of DC-SOFC anode. Among the Ti-doped samples (x = 0.1–0.3), PBFT0.2 shows the largest adsorption capacity for CO and the highest electrical conductivity in air. Using pure nano-activated carbon as a fuel, the single cell supported by La0.9Sr0.1Ga0.8Mg0.2O3 electrolyte with PBFT0.2 as an anode achieves the maximum power densities of 527, 281, and 146 mW·cm–2 at 800, 750, and 700 °C, respectively. The above excellent performance of PBFT0.2 indicates that it has great potential for application in DC-SOFC anode.

Synthesis and Electrochemical Performance of Layered Double Perovskite Anode for Direct Carbon Solid Oxide Fuel Cell

As an energy conversion device, Direct carbon solid oxide fuel cell (DC-SOFC) can efficiently convert the chemical energy contained in carbonaceous fuels into electricity. It may be an efficient and clean way to utilize carbon fuels. In this paper, (PrBa)0.95Fe1.7Ti0.2Co0.1O6-δ (PBFTC), a perovskite oxide with A-site ordered layered structure, is successfully prepared via a sol-gel method and it has been studied as the DC-SOFC anode material. Doping of Ti and the ordered layered structure make PBFTC achieve good structural stability. The phase structure of PBFTC remained unchanged after being treated in both H2 and carbon reducing atmosphere so that it can be applied in DC-SOFC anode. Using PBFTC as the anode material, a peak power density as high as 386 mW·cm−2 is achieved at 800 °C when using pure activated carbon as fuel.

A high-performance direct carbon solid oxide fuel cell powered by barium-based catalyst-loaded biochar derived from sunflower seed shell

Direct carbon solid oxide fuel cell (DC-SOFC) is one of the most attractive thesises for clean and efficient utilization of solid carbon to produce electricity. According to the operating principle, DC-SOFC performance is closely associated with the carbon sources and catalysts of the reverse Boudouard reaction. Here, we report a high-performance DC-SOFC powered by the biochar derived from sunflower seed shell (SSS) with barium-based catalyst loaded. The physicochemical properties of the SSS biochar are characterized and analyzed detailly. The electrolyte-supported symmetrical SOFC fueled with the SSS biochar gives an output of 216 mW cm−2 at 850 °C, indicating a great potential of the SSS biochar for DC-SOFCs. More importantly, the best output of 265 mW cm−2 and open circuit voltage of 1.03 V are obtained from DC-SOFC operated on 5 wt% barium-loaded SSS biochar, which is comparable to the output of 273 mW cm−2 from the hydrogen-fueled SOFC at 850 °C with the identical configuration. The superiorities of the SSS biochar and barium-based catalyst are also reflected in the operation stability and fuel utilization of DC-SOFCs. The discharge platforms are stable and the longest lifetime is up to 28.0 h under 50 mA with the fuel utilization of 31.3%, which is very excellent and competitive. This work provides a new idea for the effective utilization of the SSS biochar and other biomass for DC-SOFCs.

A vanadium-doped La0.5Sr0.5FeO3-δ perovskite as a promising anode of direct carbon solid oxide fuel cells for brown coal utilization

Direct carbon solid oxide fuel cell (DC-SOFC) is a potential and prospective technology to convert chemical energy from real-world coal fuels into electricity with environment friendliness and high efficiency. However, the limited three-phase reaction boundaries and the challenge of sluggish carbon oxidation activity have always hindered the development and application of DC-SOFCs. On this account, here vanadium-doped B-site-deficient La0.5Sr0.5FeO3-δ (LSFVx, x = 0, 0.05, 0.10, 0.15) perovskite materials are synthesized and developed as the anode of DC-SOFCs for brown coal utilization. The best electrochemical performance at 850 ℃ belongs to the LSFV0.1 cell, delivering a maximum power density of 249 mW cm−2, and the lowest polarization resistance of 0.37 Ω cm2,along with the longest discharging time up to 8.65 h. Compared with the pure LSF, the electrochemical performances of all perovskites doped with vanadium have been greatly promoted, demonstrating that the doping of vanadium can effectively expand the three-phase reaction boundaries of the cell, thus enhance the catalytic activity due to the promotion of oxygen deficiencies and tailing of electronic structures.

Application of biochar derived from used cigarette filters in direct carbon solid oxide fuel cell

As a typical waste, used cigarette filters (UCFs) are difficult to biodegrade and harmful to the environment. The direct carbon solid oxide fuel cell (DC-SOFC) is an energy conversion device that can utilize carbon directly, including biochar, as fuel. We report a superior DC-SOFC powered by Fe-loaded UCF biochar in this paper. The microstructure and composition are characterized, indicating that the UCF biochar is micron-sized and contains metal elements such as K and Ca that are beneficial to the performance of DC-SOFC. The peak power density of the cell fueled by pure UCF biochar is 308 mW cm−2 and increases to 341 mW cm−2 after loading Fe as the catalyst, which is comparable to that of the cell with Fe-loaded activated carbon (368 mW cm−2). It proves the feasibility of the UCF biochar as fuel for DC-SOFCs, providing a theoretical basis and technical demonstration for the disposal and transformation of solid waste.

Highly efficient direct carbon solid oxide fuel cells operated with camellia oleifera biomass

Direct carbon solid oxide fuel cells (DC-SOFCs), energy conversion devices with an all-solid-state structure, utilize solid carbon as a fuel to generate electricity in a green and efficient manner. Recently, the use of biomass-derived carbon as a DC-SOFC fuel has become a key research topic owing to the abundance and renewability of biomass. Thus far, for the majority of studies, an anaerobic pyrolysis process is usually needed for converting the biomass to biochar prior to applying DC-SOFCs. In this study, DC-SOFCs were assembled with perovskite-type La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) and Ag-Gd0.2Ce0.8O2-δ as the electrolyte and electrodes, respectively. The electrochemical performance and stability were evaluated for two types of DC-SOFCs: those filled with Camellia oleifera shell biomass as the fuel and those filled with biochar derived from the biomass. The biomass-filled DC-SOFC achieved a maximum power density of 306 mW cm−2 at 800°C, which is close to that of the biochar-filled DC-SOFC (317 mW cm−2). Moreover, discharge test results of constant current indicate that biomass-filled DC-SOFCs have higher fuel utilization. This study verifies the feasibility and potential of loading biomass directly into DC-SOFCs as a carbon source, and reveals that, compared with DC-SOFCs operated with biochar, biomass-filled DC-SOFCs can deliver remarkable electrochemical performance and stability. Thus, a simpler and more convenient way to generate electricity through efficient and clean utilization of biomass energy is identified.

Direct carbon solid oxide fuel cells powered by rice husk biochar

The inefficient application of fossil energy is one of the fundamental factors leading to global warming. Bioenergy is a renewable energy and also a carbon-neutral energy, with advantages of extensive sources, diverse products, and environmental friendliness. Direct carbon solid oxide fuel cell (DC-SOFC) is a novel high-efficient bioenergy technology, which is able to directly convert the chemical energy of biochar into power. A biochar derived from rice husk is applied to power an electrolyte-supported DC-SOFC. The maximum power density of the cell with pure rice husk biochar is 135 mW cm−2 at 850°C, which enhances to 214 mW cm−2 after using a Boudouard reaction catalyst. The microstructures, components and thermochemical parameters of the biochar are characterized and analyzed. The results show that the microstructure of the rice husk biochar is rough and porous. Na, K, Mg, Al, and other elements are found to present in the biochar. The physicochemical properties of the biochar and the enhanced electrical output of the DC-SOFCs are demonstrated and discussed in detail.

A novel Boudouard reaction catalyst derived from strontium slag for enhanced performance of direct carbon solid oxide fuel cells

Direct carbon solid oxide fuel cells (DC-SOFCs) are recognized as an efficient energy conversion device. With regard to their working principle, the reverse Boudouard reaction rate is the crucial factor influencing cell performance. In this work, a new-type catalyst derived from industrial strontium slag (SS) was first introduced into DC-SOFCs to promote the reverse Boudouard reaction and power output. The physicochemical properties of SS and strontium slag-derived catalyst (SSC) were characterized by SEM/EDS, BET, XRD and XRF techniques in detail. The advantages of SS and SSC were reflected in the enhanced DC-SOFC performance and high fuel utilization. The single cell powered by SSC-loaded carbon exhibited the best output of 248 mW cm−2 at 850 °C. This result was comparable to the 274 mW cm−2 output of a hydrogen-fueled SOFC due to the superior catalytic activity of metallic catalysts toward carbon gasification. The superiority of the SSC was also observed in the durable operation of the corresponding DC-SOFCs, which lasted for 32.0 h at 50 mA with the fuel utilization of 25.6%. This work provides a new channel for green and efficient utilization of strontium slag and other industrial residues, and a novel option to the development of energy conversion technology.