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High-purity of hydrogen is vital to the guarantee of end usage in proton exchange membrane fuel cell (PEMFC) electric vehicles (EVs) with superior durability and low expense. However, the currently employed hydrogen, primarily from fossil fuel, still contains some poisoning impurities that significantly affect the durability of PEMFCs. Here, we investigate the poisoning effect of several typical hydrogen impurities (S2–, Cl–, HCOO– and CO32–) on the hydrogen oxidation reaction (HOR) of the state-of-the-art carbon-supported platinum (Pt/C) catalyst used in the PEMFC anode. Electrochemical results indicate that the electrochemically active surface area of Pt/C is hampered by these hydrogen impurities with reduced effective Pt reactive sites due to the competitive adsorption against hydrogen at Pt sites showing the extent of the poisoning on Pt sites in the order: S2– > Cl– > HCOO– > CO32–. Density functional theory calculations reveal that the adsorption energy of S2– on Pt (111) is greater than that of Cl–, HCOO– and CO2, and the electronic structure of Pt is found to be changed due to the adsorption of impurities showing the downshift of the d-band centre of Pt that weakens the adsorption of hydrogen on the Pt sites. This work provides valuable guidance for future optimization of hydrogen quality and also emphasizes the importance of anti-poisoning anode catalyst development, especially towards H2S impurities that seriously affect the durability of PEMFCs.

Renewable power-derived green hydrogen distributed via natural gas networks is considered one of the viable routes to drive the decarbonization of transportation and distributed power generation, while a trace amount of sulfur impurities is one of the key factors that affect the durability and life cycle expense of proton-exchange membrane fuel cells (PEMFCs) for end users. Herein, we explore the underlying effect of sulfur resistance for Pt-based hydrogen oxidation reaction (HOR) electrocatalysts devoted to high-performance and durable PEMFCs. Two typical electrocatalysts, Pt/C with pure Pt nanoparticles (NPs) and PtCo/C with Pt

Hydrogen fuel cells are regarded as a promising new carbon mitigation strategy to realize carbon neutrality. The exploitation of robust and efficient cathode catalysts is thus vital to the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, we demonstrate a facile and scalable surface engineering route to achieve superior durability and high activity of a Pt-based material as a PEMFC cathode catalyst through a controllable liquid-phase reduction approach. The proposed surface engineering strategy by modifying Pt/C reduces the oxygen content on the carbon support and also decreases the surface defects on Pt nanoparticles (NPs), which effectively alleviate the corrosion of carbon and inhibit the detachment, agglomeration, and growth of Pt NPs. The resulting catalyst exhibits superior durability after a 10,000 potential cycling test in an acid electrolyte─outperforming commercial Pt/C. Moreover, the catalyst also demonstrates an improved oxygen reduction reaction (ORR) activity in comparison to commercial Pt/C by virtue of the high content of metallic Pt and the weakened Pt-OH bonding that releases more Pt active sites for ORR catalysis. Most importantly, the developed catalyst shows outstanding PEMFC performance and excellent long-term durability over 50 h of a constant-current test and 100 h of a load-cycling operation. This effective route provides a new avenue for exploiting robust Pt-based catalysts with superior activity in practical applications of PEMFCs.

Durability is one of the critical issues to restrict the commercialization of proton exchange membrane fuel cells (PEMFCs) for the vehicle application. The practical dynamic operation significantly affects the PEMFCs durability by corroding its key components. In this work, the degradation behavior of a single PEMFC has been investigated under a simulated automotive load-cycling operation, with the aim of revealing the effect of load amplitude (0.8 and 0.2 A/cm2 amplitude for the current density range of 0.1−0.9 and 0.1−0.3 A/cm2, respectively) on its performance degradation. A more severe degradation on the fuel cell performance is observed under a higher load amplitude of 0.8 A/cm2 cycling operation, with ∼10.5% decrease of cell voltage at a current density of 1.0 A/cm2. The larger loss of fuel cell performance under the higher load amplitude test is mainly due to the frequent fluctuation of a wider potential cycling. Physicochemical characterizations analyses indicate that the Pt nanoparticles in cathodic catalyst layer grow faster with a higher increase extent of particle size under this circumstance because of their repeated oxidation/reduction and subsequent dissolution/agglomeration process, resulting in the degradation of platinum catalyst and thus the cell performance. Additionally, the detected microstructure change of the cathodic catalyst layer also contributes to the performance failure that causes a distinct increase in mass transfer resistance.

High quality of hydrogen is the key to the long lifetime of proton-exchange membrane fuel cell (PEMFC) vehicles, while trace H

The poor electronic conductivity and low intrinsic electrocatalytic activity of metal organic frameworks (MOFs) greatly limit their direct application in electrocatalytic reactions. Herein, we report a conductive two-dimensional

The poor electronic conductivity and low intrinsic electrocatalytic activity of metal organic frameworks (MOFs) greatly limit their direct application in electrocatalytic reactions. Herein, we report a conductive two-dimensional π–d conjugated Ni and Co bimetal organic framework (MOF)—NiCo-(2,3,6,7,10,11-hexaiminotriphenylene) (NiCo-HITP) nanorods decorated with highly dispersed Co3O4 nanoparticles (NPs) as a promising bi-functional electrocatalyst towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through an effective and facile strategy by modifying the rod-shaped -Ni3HITP2 crystals using cobalt ions. The triggered electrocatalytic activity of the resulting MOF-based materials was achieved by increasing the electrical conductivity (7.23 S cm−1) originated from Ni3HITP2 substrate and also by creating the cooperative catalysis sites of Co–N x and Co3O4 NPs. Optimized syntheses show a promising ORR activity with a high half-wave potential (0.77 V) and also a significantly improved OER activity compared with pure Ni3HITP2 in alkaline electrolyte. Furthermore, a rechargeable Zn–air battery using the as-prepared material as air-cathode also shows a high power density (143.1 mW cm−2)—even comparable to a commercial Pt/C-RuO2-based battery. This methodology offers a new prospect in the design and synthesis of non-carbonized MOF bi-functional electrocatalysts for efficient catalysis towards ORR and OER.

Next generation digital subscriber line (NG-DSL) gains high efficiency by taking scheme of base-band orthogonal frequency-division multiplexing (OFDM) modulation with very large subcarrier number and very high modulation levels. However, it requires high sampling synchronization precisions since sampling frequency offset (SFO) will introduce inter-carrier interference (ICI) and degrade performance. To achieve a higher synchronization, we propose a new blind SFO estimation algorithm by segmenting the OFDM symbols and then estimate SFO in iterations. The new algorithm has higher precision and faster convergence speed than the traditional pilot-aided algorithms under the condition of large subcarrier number and high modulation levels.

For the channel offset caused by the time offset(TO) of the MIMO-OFDM system, we propose a new high-precision and low complexity new channel estimation algorithms, which is based on least squares(LS) method to solve the problem that we need to send a lot of pilot symbols to estimate the channel coefficient again when the fractional timing offset is present, which greatly reduces the complexity of the system. Meanwhile, we combine the new algorithm and Vectoring technology, so that it allows multiple transmitted signals through the down-link pre-coding matrix and the actual channel to each receiver, completely eliminating the multiple user interference caused by transmitted signals of multiple users and accurately extracting the signal of each user. Simulation experiments prove that the new algorithms have good estimation performance.