Oxygen reduction reaction performance of Fe-N-C catalyst with dual nitrogen sourceZhao, Yuan; Wang, Quan; Hu, Rongrong; Liu, Wenqiang; Zhang, Xiaojuan; Wang, Wei; Alonso-Vante, Nicolas; Zhu, Dongdong
2024 Frontiers in Energy
doi: 10.1007/s11708-024-0956-2
Fe-N-C catalysts are potential substitutes to displace electrocatalysts containing noble chemical elements in the oxygen reduction reaction (ORR). However, their application is hampered by unsatisfactory activity and stability issues. The structures and morphologies of Fe-N-C catalysts have been found to be crucial for the number of active sites and local bonding structures. In this work, dicyandiamide (DCDA) and polyaniline (PANI) are shown to act as dual nitrogen sources to tune the morphology and structure of the catalyst and facilitate the ORR process. The dual nitrogen sources not only increase the amount of nitrogen doping atoms in the electrocatalytic Fe-C-N material, but also maintain a high nitrogen-pyrrole/nitrogen-graphitic: (N-P)/(N-G) value, improving the distribution density of catalytic active sites in the material. With a high surface area and amount of N-doping, the Fe-N-C catalyst developed can achieve an improved half-wave potential of 0.886 V (vs. RHE) in alkaline medium, and a better stability and methanol resistance than commercial Pt/C catalyst.
Improvement of durability of membrane electrode assembly by frame sealing structure in temperature shockWang, Yanbo; Chu, Tiankuo
2024 Frontiers in Energy
doi: 10.1007/s11708-024-0955-3
The frame of membrane electrode assembly (MEA) influences the durability of proton exchange membrane fuel cell (PEMFC). In this paper, the thermal shock bench was applied as an accelerated aging test to explore the effect of frame sealing structure on MEA durability at different temperatures. Analysis of scanning electron microscope (SEM) images reveals that thermal shock results in the formation of cracks on the exposed proton exchange membrane (PEM) at the gap between the frame and the active area. Moreover, it breaks the bonding interface between the frame and the membrane and leads to the debonding of the adhesive, which exacerbates the risk of crossover of the reactant gas. A comparison of the single-layer and improved double-layer frame structures reveal that the mechanical damage is caused by frequent membrane wrinkles in the gap under temperature shock. However, addition of a cushion layer improves the continuity between the frame and the active area, and reduces deformation of the membrane, thereby preventing membrane damage.
Low-carbon collaborative dual-layer optimization for energy station considering joint electricity and heat demand responseXu, Shaoshan; Wu, Xingchen; Shen, Jun; Hua, Haochen
2024 Frontiers in Energy
doi: 10.1007/s11708-024-0958-0
In the park-level integrated energy system (PIES) trading market involving various heterogeneous energy sources, the traditional vertically integrated market trading structure struggles to reveal the interactions and collaborative relationships between energy stations and users, posing challenges to the economic and low-carbon operation of the system. To address this issue, a dual-layer optimization strategy for energy station-user, taking into account the demand response for electricity and thermal, is proposed in this paper. The upper layer, represented by energy stations, makes decisions on variables such as the electricity and heat prices sold to users, as well as the output plans of energy supply equipment and the operational status of battery energy storage. The lower layer, comprising users, determines their own electricity and heat demand through demand response. Subsequently, a combination of differential evolution and quadratic programming (DE-QP) is employed to solve the interactive strategies between energy stations and users. The simulation results indicate that, compared to the traditional vertically integrated structure, the strategy proposed in this paper increases the revenue of energy stations and the consumer surplus of users by 5.09% and 2.46%, respectively.
Performance-enhanced direct ammonia protonic ceramic fuel cells using CeO2-supported Ni and Ru catalyst layerLi, Xiaoxiao; Chen, Jiangping; Huang, Yunyun; Fang, Huihuang; Chen, Chongqi; Zhong, Fulan; Lin, Li; Luo, Yu; Wang, Yuqing; Jiang, Lilong
2024 Frontiers in Energy
doi: 10.1007/s11708-024-0959-z
Ammonia is an exceptional fuel for solid oxide fuel cells (SOFCs), because of the high content of hydrogen and the advantages of carbon neutrality. However, the challenge lies in its unsatisfactory performance at intermediate temperatures (500–600 °C), impeding its advancement. An electrolyte-supported proton-ceramic fuel cell (PCFC) was fabricated employing BaZr0.1Ce0.7Y0.2O3−δ (BZCY) as the electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) as the cathode. In this study, the performance of PCFC using NH3 as fuel within an operating temperature range of 500–700 °C was improved by adding an M(Ni,Ru)/CeO2 catalyst layer to reconstruct the anode surface. The electrochemical performance of direct ammonia PCFC (DA-PCFC) were improved to different extents. Compared to H2 as fuel, the degradation ratio of peak power densities (PPDs) of Ni/CeO2-loaded PCFC fueled with NH3 decreased at 700–500 °C, with a decrease to 13.3% at 700 °C and 30.7% at 500 °C. The findings indicate that Ru-based catalysts have a greater promise for direct ammonia SOFCs (DA-SOFCs) at operating temperatures below 600 °C. However, the enhancement effect becomes less significant above 600 °C when compared to Ni-based catalysts.