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An advanced cathode design can improve the power performance and durability of proton exchange membrane fuel cells (PEMFCs), thus reducing the stack cost of fuel cell vehicles (FCVs). Recent studies on highly active Pt alloy catalysts, short-side-chain polyfluorinated sulfonic acid (PFSA) ionomer and 3D-ordered electrodes have imparted PEMFCs with boosted power density. To achieve the compacted stack target of 6 kW/L or above for the wide commercialization of FCVs, developing available cathodes for high-power-density operation is critical for the PEMFC. However, current developments still remain extremely challenging with respect to highly active and stable catalysts in practical operation, controlled distribution of ionomer on the catalyst surface for reducing catalyst poisoning and oxygen penetration losses and 3D (three-dimensional)-ordered catalyst layers with low Knudsen diffusion losses of oxygen molecular. This review paper focuses on impacts of the cathode development on automotive fuel cell systems and concludes design directions to provide the greatest benefit.

The development of new electrode fabrication approaches from highly active electrocatalysts to replace the state-of-the-art Pt/C is most desirable for enhancing power performance and durability in proton exchange membrane fuel cells. However, the deployment of advanced, often shape-controlled Pt alloy electrocatalysts in actual electrodes remains challenging due to their small quantities in preparation and poor power performance in operating fuel cells. In this study, a new electrocatalyst approach is presented for Au integrated one-dimensional AgPt alloy nanorods. The atom arrangement is tuned through precisely controlling the metal ion reduction procedure to improve the catalyst activity. With 5 at% Au, nanorods with an average length of 20 nm and diameter of 3–4 nm are achieved. The test of Au–AgPt nanorods as cathode catalysts shows 1.2-fold higher fuel cell power density than that for commercial Pt/C catalysts, and a lower decline rate of 39.63% than 44.19% after an accelerated degradation test.

The excellent performance and safety of direct formic acid fuel cells (DFAFCs) promote them as potential power sources for portable electronic devices. However, their real application is still highly challenging due to the poor power performance and high complexity in the fabrication of catalyst electrodes. In this work, we demonstrate a new gas diffusion electrode (GDE) with ultrathin PtCu alloy nanowire (NW) arrays in situ grown on the carbon paper gas diffusion layer surface. The growing process is achieved by a facile template- and surfactant-free self-growth assisted reduction method at room temperature. A finely controlled ion reduction process tunes the nucleation and crystal growth of Pt and Cu leading to the formation of alloy nanowires with an average diameter of about 4 nm. The GDE is directly used as the anode for DFAFCs. The results in the half-cell GDE measurement indicate that the introduction of Cu in PtCu NWs boosts the direct oxidation pathway for formic acid. The Pt

This article explores the materials used in the components in the polymer electrolyte membrane fuel cell (PEMFC), namely; the polymer electrolyte membrane, the flow field plate, and the gas diffusion layer. Each section deals with one of the listed components considering: (a) its function within a PEMFC, (b) the material properties influencing its operation and performance, (c) the main materials discussed in the literature, and (d) the state-of-art and current research activity.

The excellent catalytic activities and stability of one-dimensional (1D) AgPt alloy nanostructures have been well reported toward the oxygen reduction reaction (ORR). However, their real application in proton exchange membrane fuel cells (PEMFCs) is still highly challenging due to the great difficulties in their preparation and fabrication into practical electrodes. By a facile self-growth assisted reduction method, ultrathin single-crystal AgPt alloy nanorods (NRs) with a diameter of 3–4 nm are uniformly grown on a carbon support through a finely controlled ion reduction process tuning the nucleation and growth of Pt and Ag. Enhanced power performance is successfully demonstrated in the single-cell test. With 50 at% Ag, the AgPt NR/C electrode shows 1.16-fold power density and 1.22-fold mass activity compared to the Pt NR/C electrode, and 1.14 and 1.51-fold compared to the commercial Pt/C electrode, respectively. Comparable durability is also established in fuel cells by using the accelerated degradation test, although Ag is included.

The modification of Pt/C catalyst by using ionic liquids to improve their catalyst activities has been reported by many researchers, but their practical behavior in operating fuel cells is still unknown. In this work, we study the ionic liquid modified Pt/C nanoparticle catalysts within cathodes for proton exchange membrane fuel cells. The influence of the ionic liquid amount, adsorption times and dispersing solvents are investigated. The experiment results show the best performance enhancement is achieved through two-time surface modification with 2 wt-% ionic liquid solution. The mechanisms are explored with the attribution to the high oxygen solubility in the ionic liquid enabling an improved oxygen diffusion in micropores and to good hydrophobicity facilitating water expelling from the active sites in fuel cell operation.

High performing proton exchange membrane fuel cells (PEMFCs) that can operate at low relative humidity is a continuing technical challenge for PEMFC developers. In this work, micro-patterned membranes are demonstrated at the cathode side by solution casting techniques using stainless steel moulds with laser-imposed periodic surface structures (LIPSS). Three types of patterns, lotus, lines, and sharklet, are investigated for their influence on the PEMFC power performance at varying humidity conditions. The experimental results show that the cathode electrolyte pattern, in all cases, enhances the fuel cell power performance at 100% relative humidity (RH). However, only the sharklet pattern exhibits a significant improvement at 25% RH, where a peak power density of 450 mW cm−2 is recorded compared with 150 mW cm−2 of the conventional flat membrane. The improvements are explored based on high-frequency resistance, electrochemically active surface area (ECSA), and hydrogen crossover by in situ membrane electrode assembly (MEA) testing.

A clear understanding of catalytic activity enhancement mechanisms in fuel cell operation is necessary for a full degree translation of the latest generation of non-Pt/C fuel cell electrocatalysts into high-performance electrodes in proton-exchange membrane fuel cells (PEMFCs). In this work, PtNi nanowire (NW) array gas diffusion electrodes (GDEs) are fabricated from Pt NW arrays with Ni impregnation. A 2.84-fold improvement in the oxygen reduction reaction catalytic activity is observed for the PtNi NW array GDE (cf. the Pt NW array GDE) using half-cell GDE measurement in a 0.1 M HClO4 aqueous electrolyte at 25 °C, in comparison to only a 1.07-fold power density recorded in the PEMFC single-cell test. An ionomer is shown to significantly increase the electrochemically active surface area of the GDEs, but the PtNi NW array GDE suffers from Ni ion contamination at a high temperature, contributing to decreased catalytic activities and limited improvement in operating PEMFCs.

Two time-scale receding horizon optimal control (TTRHOC) of greenhouse cultivation is investigated. Recent developments enable closure of the outer-loop of this control system because they facilitate on-line recomputation of the optimal control of the slow dynamics on a daily basis. This paper quantifies the benefits obtained from having an outer closed-loop that counteracts errors and changes concerning predictions of crop growth, long-term weather, revenues obtained from selling crops and costs to control greenhouse climate. As a special, important case LED lighting is considered which increases both crop growth and profit. Having an outer closed-loop is especially beneficial in this case.

Ag-Functionalized CuWO 4 /WO 3 heterostructures were successfully prepared via a polyvinyl pyrrolidone (PVP)-assisted sol-gel (PSG) route. Thin films prepared via electrophoretic deposition were used as photoanodes for photoelectrochemical (PEC) water splitting. Compared to pristine CuWO 4 and WO 3 films, a significant enhancement of the photocurrent (3-4 times) at the thermodynamic potential for oxygen evolution (0.62 V vs. Ag/AgCl, pH 7) was obtained for the Ag-functionalized CuWO 4 /WO 3 photoanodes. The obtained enhancement is shown to be derived from a synergic contribution of heterostructure formation (CuWO 4 /WO 3 ) and improvements of light utilization by Ag-induced surface plasmon resonance (SPR) effects. Accordingly, a photocurrent of 0.205 mA cm -2 at 0.62 V vs. Ag/AgCl under neutral conditions (without hole scavengers) under front-side simulated AM1.5G illumination was achieved. A detailed analysis of the obtained PEC data alongside performed impedance measurements suggests that charge seperation is significantly improved for the prepared Ag-functionalized CuWO 4 /WO 3 photoanodes. Our work offers beneficial insights to design new plasmonic metal/heterostructured nanocomposites for energy conversion applications.

Photocatalysis has proved its potential in cleaving the Cβ-O linkages between the natural aromatic units in lignin biomass and converting abundant lignin biomass to valuable aromatic monomer products. However, the slow reaction rate and low selectivity for aromatic monomers still hinder its future industrial implementation. To address these challenges in photocatalytic Cβ-O bond fragmentation, a Zn/S rich phase zinc indium sulfide photocatalyst was developed to promote hydrogenolysis of Cβ-O linkages in lignin. In this work, water is for the first time, used as the hydrogen donor and can significantly promote the photocatalytic process by eliminating the limitation of protons supply. The reaction selectivity for aromatic monomers increased by 170% and PP-ol conversion rate raised by 58% comparing to the reaction condition without water. Notably, complete conversion of lignin model compounds with an expectational improved reaction rate and over 90% selectivity for aromatic monomers have been achieved in this study. The isotopic labeling experiments and kinetic isotope effects (KIE) measurements also indicate that the dissociation of the O–H bond in water which provides protons to the Cβ-O bond hydrogenolysis process is a critical step to this reaction. Mechanistic studies reveal that the dehydrogenated radical intermediates are initially generated by the oxidation of photogenerated holes, and the protons generated from photocatalytic water splitting are superior in facilitating the subsequently hydrogenolysis process of Cβ-O bonds. This study provides a new and effective strategy to promote the cleavage of Cβ-O linkages and is helpful for the future development of photocatalytic lignin valorization.

This work investigates the catalytic performance of bimetallic Ni-Cu/Al2O3 catalysts for syngas production by methanol steam reforming. The synthesis and characterization of a series of Nix-Cuy/Al2O3 catalysts with various stoichiometric fractions (x = 10, 7, 5, 3 and 0 wt% and y = 0, 3, 5, 7 and 10 wt% to Al2O3 support, respectively) are investigated and discussed. The catalytic performance is evaluated experimentally at temperature range of 225–325 °C. Both mono-metallic catalyst (10wt%Cu/Al2O3 and 10wt%Ni/Al2O3) and bi-metallic catalysts (7wt%Cu-3wt%Ni/Al2O3, 5wt%Cu-5wt%Ni/Al2O3 and 3wt%Cu-7wt%Ni/Al2O3) are synthesized using an impregnation method and characterized by means of SEM, temperature programmed reduction (TPR), BET analysis, XRD and TGA. It is found that the bimetallic Ni-Cu catalyst had a strong influence on the amount of CO2 and CO produced due to the different selectivity towards the water gas shift reaction and methanol decomposition reaction. The increase of the Ni content leads to an increase in CO and decrease in CO2 yields. The bimetallic catalyst did not produce CH4, revealing that Cu alloying in Ni catalyst had an inhibiting effect for CO and/or CO2 hydrogenation.

Improving cathode performance at a lower Pt loading is critical in commercial PEMFC applications. A novel Pt nanowire (Pt-NW) cathode was developed by in-situ growth of Pt nanowires in carbon matrix consisting Pt nanoparticles (Pt-NPs). Characterization of TEM and XRD shows that the pre-existing Pt-NPs from Pt/C affect Pt-NW morphology and crystallinity and Pt profile crossing the matrix thickness. The cathode with Pt-NP loading of 0.005 mgPt-NP cm−2 and total cathode Pt loading of 0.205 mgPt cm−2 has the specific current density of 89.56 A gPt−1 at 0.9 V, which is about 110% higher than that of 42.58 A gPt−1 of the commercial gas diffusion layer (GDE) with Pt loading of 0.40 mg cm−2. When cell voltage is below 0.48 V, the Pt-NW cathode has better performance than the commercial GDE. It is believed that the excellent performance of the Pt-NW cathode is attributed to Pt-NP induction, therefore producing unique Pt-NW structure and efficient Pt utilization. A Pt-NW growth mechanism was proposed that Pt precursor diffuses into the matrix consisting of pre-existent Pt-NPs by concentration driving, and Pt-NPs provide priority sites for platinum depositing at early stage and facilitate Pt-NW growth.

Gas diffusion layer (GDL), consisting of a microporous layer (MPL) and a carbon fibre substrate, is one of the major components in proton exchange membrane fuel cells (PEMFCs). In gas diffusion electrodes (GDEs) with in-situ grown aligned Pt nanowire (NW) catalysts, the GDL can also provide an important function in controlling the growth and distribution of the Pt nanowires. In this work, a systematic investigation is conducted to evaluate the evolution of the GDL structure on the PtNW growth process to prepare GDEs. The influence mechanisms including carbon loading, carbon composition and polytetrafluoroethylene (PTFE) loading in the MPL and PTFE in the carbon fibre substrate on the electrode power performance are studied in detail. An optimum structure for MPL, 4 mg cm−2 carbon loading with an equal amount of carbon black (CB) and acetylene black (AB), plus 5% PTFE loading, is deserved. This GDL structure can provide suitable substrate coverage, reasonable surface nucleation sites and required hydrophobicity for the in-situ growth of PtNWs. The results indicate that the GDL features play a significant role in the growth and distribution of the obtained Pt nanowires to achieve high performance GDEs for PEMFC application.

We used first principles calculations based on density functional theory with generalized gradient approximation to investigate and compare the structural, electronic and optical properties of two photoanode materials, ZnV2O6 and Zn2V2O7, for use in photocatalytic water splitting. After geometry optimization, the calculated structural parameters evince a satisfactory agreement with the reported experimental results indicating that the used method and conditions are suitable. The electronic structures demonstrate that both photocatalysts possess favorable band gaps (2.31 and 2.52 eV) and appropriate band edge positions for oxygen evolution reaction under solar radiation. The relatively light effective masses at the valence band maximum and conduction band minimum are expected to result in enhanced photocatalytic activity due to lower recombination probability of the photogenerated electrons and holes. The analysis of electronic density of states reveal that the higher coordination number of vanadium in ZnV2O6 with respect to Zn2V2O7 causes more delocalisation of bands owning to lower V-V and O-O distances in conduction and valence bands, respectively. Moreover, the origins of features that appear in solar energy harvesting characteristics (dielectric function and optical absorption coefficient) have been discussed for solar water splitting in detail.

The benefits of introducing heating, CO2 supply, ventilation and LED lighting in a Chinese solar greenhouse are investigated. To that end, a two time-scale receding horizon optimal control system is assumed to accompany the introduction. The model of the Chinese solar greenhouse dynamics used by the optimal control system incorporates the effect of a north wall, present in any Chinese solar greenhouse. This wall stores heat during the day and releases heat at night to improve temperature. The optimal control system also takes control of a thermal blanket, that can be partly opened and closed to reduce heat loss to the environment. Apart from performing real-time optimal control, the optimal control system enables computation of improvements in terms of profit. Finally the feasibility of real-time implementation of the two time-scale receding horizon optimal control system on a personal computer is verified.

A new plasmonic Ag hybridized CuWO4/WO3 heterostructure was successfully synthesized via a ligand-assisted sol gel method. The as-prepared plasmonic nanohybrid was thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, photoluminescence (PL) spectrometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis and electrochemical impedance spectroscopy (EIS). Moreover, the photocatalytic activity was evaluated by photo-degradation of methylene blue (MB) under visible light irradiation. The results indicate that the as-prepared plasmonic Ag–CuWO4/WO3 nanohybrid (compared to pure WO3) with high surface area exhibits significant enhancement in photocatalytic behavior in the visible spectrum, which can be ascribed to combined effects, including the more effective absorption of visible light, lower bulk resistance, effective separation/transfer of photo-generated charge carriers and reduced electron/hole recombination which results from the contribution of hetero-junction and plasmonic Ag incorporation. In addition, a possible mechanism for the photo-degradation process of the hetero-structured Ag nanohybrid is proposed. Finally, the metal/semiconductor nanohybrid displayed sufficient recyclability with respect to photocatalytic activity, making it a promising candidate for pollutant degradation and energy conversion applications.

This paper reports the results of experimental work carried out on a micro-tubular solid oxide fuel cell tri-generation systemthat uses the waste heat from the fuel cell for dehumidification and cooling though the integration of an open cycle liquid desiccant dehumidification and cooling system. The experimental results demonstrate regeneration of the potassium formate solution using the thermal output from the SOFC in the first of its kind tri-generation system. Optimisation has shown that a 2.2L.min-1 regenerator desiccant volumetric flow facilitates best performance.When integrated with the micro-SOFC, the open cycle desiccant system demonstrates a COP of approaching 0.7, an encouraging value for a waste heat driven cooling system of this capacity. A tri-generation performance analysis is presented which serves to demonstrate the novel system operating in a building. The system achieved an electrical efficiency of 11% and regeneration efficiency of approximately 37%. The electrical efficiency is lower than that predicted by the company supplying the micro-tubular SOFC, because the unit suffered sulphur poisoning during preliminary tests. The electrical power output decreased from 250W to 150W, which reduced the electrical efficiency from around 18% to 11% and the overall efficiency from approximately 45% to just over 37%. Low temperature (33-36°C) regeneration was demonstrated.

This chapter starts with a brief introduction to the proton exchange membrane fuel cell history and principles. We then highlight the requirements in porosity in catalyst electrodes, followed by the electrode structure design and porosity characterization. Recent advancements in catalysts and supports are discussed, especially the development of three-dimensional (3D) electrodes from aligned 1D nanostructures. The challenge and opportunities for future research are finally addressed.

Proton Exchange Membrane fuel cells (PEMFCs) are becoming an increasingly promising piece of power generation technology that can fit into the changing economy as we strive towards a sustainable energy-based future. However, PEMFCs struggle to meet the energy demands of the world, falling short of the capability of other energy sources such as fossil fuels, mainly due to price and energy output compared to the already establish combustion engines. Looking internally into the PEMFC itself, one of the main issues is the limitations of the electrode-membrane interface leading to low ion transfer performance from the catalyst layer to polymer electrolyte membrane. If we can improve the cathode-membrane interface facilitating the oxygen reduction reaction (ORR) rate at the cathode, the rate limiting step, we can increase the overall performance of the fuel cell. It is believed that by increasing the interfacial area of the cathode-membrane interface, such as applying a prismatic pattern to the morphology, we can increase the active surface area for the membrane electrode assembly (MEA). By varying the prism frequency and relative height, the interfacial area can be tuned to improve the overall power performance of PEMFCs. In this work, with a LiveLink connection between Matlab and multiphysics software COMSOL, we model the electrode-membrane interface to investigate its influence on the ion-transfer performance of PEMFCs. By varying the number and size of prism peaks applied to the interface, it is shown that we can influence the fuel cell performance whilst maintaining a constant membrane and catalyst loading. The results showed, at an optimal peak frequency and relative height, an improvement of up to 25% was achieved in the power density. Although research into the prismatic morphology looks promising, there are many other potential options when looking for which morphology could yield the best overall power performance out of a PEMFC. As such, looking not only into prismatic patterning, but also a pyramidal morphology could prove beneficial. We're also looking into how the application of the roughness to the interface, created using a combination of Gaussian and Uniform wave functions, will impact any previous results observed, and allow us to simulate a model that fits better with the real-world findings. Figure 1

Monodisperse ZnFe2O4 nanospheres were succesuffully synthesized via a nonaqueous route in benzyl alcohol at low temperaure of 200 °C. It was found that the ZnFe2O4 is 7–16 nm in diameter with a large surface area of 87.40 m2/g. The gas sensor based on ZnFe2O4 nanospheres shows a high pontential for detecting low-ppm-level toluene, exhibiting a good linearity ranging from 1 to 100 ppm with a high response (100 ppm:9.98) and excellent selectivity.

316 stainless steel has been regarded as one of the promising candidates to replace graphite for bipolar plate application. However, the relatively high electrical resistance caused by the formation of passive oxide film and the insufficient corrosion resistance in long-term operation are two main concerns of 316 stainless steel bipolar plates. Low temperature active screen plasma alloying technology shows the ability to reduce electrical resistance and enhance corrosion resistance of 316 stainless steel bipolar plates to some extent, but still can not satisfy the Department of Energy (DOE) requirements. In this paper, active screen plasma co-alloying treatments with nitrogen and platinum are conducted to modify the surface of 316 stainless steel. The surface morphology, phase constitute, chemical composition and layer structure of treated 316 stainless steel are fully studied. A dense, columnar structured and single phase Pt3Fe deposition layer is produced on the surface of 316 stainless steel after treatments. Thanks to the excellent electrical conductivity and corrosion resistance of Pt3Fe, the surface electrical conductivity and corrosion resistance are greatly enhanced and satisfies the DOE requirements, contributing to the significant improvement of single cell performances.

Recent research on one-dimensional (1D) nanostructured materials brings in tremendous progress on their application as catalysts in polymer electrolyte membrane fuel cells (PEMFCs). The desired 1D nanomaterials with tailored morphology, structure and composition can potentially address many drawbacks faced by conventional Pt/C catalysts. However, their application in practical fuel cell electrodes still faces big challenge due to their unusual morphology and bulky volume. This review focuses on the recent progress from 2010 in 1D electrocatalysts for oxygen reduction reaction (ORR) and hydrocarbon (methanol, ethanol and formic acid) oxidation reaction in PEMFCs, covering Pt-based and non-Pt precious metal nanostructures, as well as non-precious metal catalysts (NPMCs). The correlations between the morphology, composition and catalytic properties of these catalysts are discussed. Critical perspectives are devoted to the increasing gap between the pure materials research and the fuel cell development in this emerging research area (222 references).

PtPd bimetallic nanodendrites (NDs), with enhanced activities from PtPd over element Pt and unique anisotropic morphology, show potential as catalysts in fuel cell applications. However, the research has been limited to pure materials, and constructing a practical fuel cell catalyst electrode from PtPd NDs still remains as a challenge. In this paper, we demonstrated, for the first time, catalyst electrodes from PtPd NDs for polymer electrolyte fuel cell (PEFC) applications. PtPd NDs are in-situ grown on large-area carbon paper gas diffusion layers (GDLs) and directly employed as cathodes in H 2 /air PEFCs. The thin catalyst layer with PtPd nanodendrites significantly reduces mass transfer resistance and a higher power performance is achieved than those based on pure Pt nanowires and Pt/C nanoparticle electrocatalysts. The crystal growth mechanisms of this advanced nanostructure on large-area support are also detailed based on the time-dependent experiments and Pd content.

Catalyst layers play an important role in direct methanol fuel cells (DMFCs), providing the reaction sites and catalysing the electrochemical reactions. For gas diffusion electrodes with Pt nanowires in-situ grown on gas diffusion layers (GDLs), the hydrophobic property of the GDL surface negatively affects the growth of the Pt nanowire catalysts, leading to the unsatisfied catalysis performance. In this work, the influence of active screen plasma (ASP) treatment temperature and duration on the growth of Pt nanowire catalyst layer was systemically studied. Single cell performance test with in-situ electrochemical surface area (ECSA) measurement were conducted to evaluate the catalysis performance of the Pt nanowire catalyst layer grown on the ASP treated carbon paper; scanning electron microscopy (SEM) was used to observe the surface morphology of the catalyst layer formed. Results revealed that the ASP treatment conducted at 120 °C for 10 min can effectively promote the growth of Pt nanowires on carbon paper gas diffusion layer, which exhibited the best catalysis performance.

Proton Exchange Membrane fuel cells (PEMFCs) are becoming an increasingly promising piece of power generation technology that can fit into the changing economy as we strive towards a sustainable energy based future. However, PEMFCs struggle to meet the energy demands of the world, falling short of the capability of other energy sources such as fossil fuels, mainly due to price and energy output compared to the already establish combustion engines. Looking internally into the PEMFC itself, one of the main issues is the limitations of the electrode-membrane interface leading to low ion transfer performance from the catalyst layer to the polymer electrolyte membrane. If we can improve the cathode-membrane interface facilitating the oxygen reduction reaction (ORR) rate at the cathode, the rate limiting step, we can increase the overall performance of the fuel cell. It is believed that by increasing the interfacial area of the cathode catalyst layer-membrane interface, by applying a prismatic pattern to the morphology, we can thus increase the active surface area for the membrane electrode assembly (MEA). By varying the frequency of prisms, and the relative height of these prisms compared to the fixed total height of the catalyst layer and membrane, the interfacial area can be increased, improving the current density, which would result in an improved overall power performance of the PEMFC. In this work, with a LiveLink connection between Matlab and multiphysics software COMSOL, we model the electrode-membrane interface to investigate the influence of the operating conditions and the morphology of the membrane surface on the ion-transfer performance of PEMFCs. By varying the number and size of prism peaks applied to the interface, it is shown that we can influence the fuel cell performance whilst maintaining a constant membrane and cathode volume as well as the amount of platinum used in the catalyst layer whilst, due to economies of scale, maintaining a similar cost per membrane compared to a flat membrane interface. Previous research has shown that there is a negative impact on power performance when the cathode catalyst layer-electrolyte interface is patterned with a low number of peaks with small relative heights compared to the total height of the electrolyte and catalyst layer. However, at higher frequencies of peaks and relative peak heights, an improvement of up to 25% was achieved in the power performance, and a 21% improvement was seen in the polarization curve. However, this model suggests perfectly smooth interfaces between the electrolyte and the catalyst layer. In reality, there would be a level of roughness to this interface, which would have an impact on the results of the simulated fuel cell performance. This research looks into how the application of the roughness to the interface, created using a combination of Gaussian and Uniform wave functions, will impact any previous results observed, and allow us to simulate a model that fits better with the real world findings. The results obtained here could help determine the appropriate parameters required to validify our experimental work, and provide reference for the future work carried out in this research field. Figure 1

Mesoporous magnetic NiFe2O4/ZnCuCr-LDH composite is synthesized by an environmental-friendly hydrothermal process from saccharin wastewater to achieve the goal of “treating the wastes with wastes”. During this process, all waste iron-catalyst and 82% of chemical oxygen demand (CODcr) are removed from the wastewater. The composite is characterized by FT-IR, XRD, SEM, EDS, TEM, XPS, BET, and VSM analyses and its potential for wastewater treatment is evaluated by Congo Red (CR) adsorption. An over 97% removal efficiency is achieved with an initial CR concentration ranging from 100–450 mg/L. The adsorption kinetic is investigated and it is found that the experimental data agrees well with the pseudo-second-order kinetic model, intra-particle diffusion and Langmuir adsorption isotherm model. Adsorption isotherm indicates a spontaneous and endothermic adsorption type. The adsorption mechanism is also explored and the important roles of electrostatic attraction and anion exchange are demonstrated.

A two-dimensional along-the-channel CFD (computational fluid dynamic) model, coupled with a two-phase flow model of liquid water and gas transport for a PEM (proton exchange membrane) fuel cell is described. The model considers non-isothermal operation and thus the non-uniform temperature distribution in the cell structure. Water phase-transfer between the vapour, liquid water and dissolved phase is modelled with the combinational transport mechanism through the membrane. Liquid water saturation is simulated inside the electrodes and channels at both the anode and cathode sides. Three types of models are compared for the HOR (hydrogen oxidation reaction) and ORR (oxygen reduction reaction) in catalyst layers, including Butler–Volmer (B–V), liquid water saturation corrected B–V and agglomerate mechanisms. Temperature changes in MEA (membrane electrode assembly) and channels due to electrochemical reaction, ohmic resistance and water phase-transfer are analysed as a function of current density. Nonlinear relations of liquid water saturations with respect to current densities at both the anode and cathode are regressed. At low and high current densities, liquid water saturation at the anode linearly increases as a consequence of the linear increase of liquid water saturation at the cathode. In contrast, exponential relation is found to be more accurate at medium current densities.

The stacking and overlapping effect of two-dimensional (2D) graphene nanosheets in the catalyst coating layer is a big challenge for their practical application in proton exchange membrane fuel cells (PEMFCs). These effects hinder the effective transfer of reactant gases to reach the active catalytic sites on catalysts supported on the graphene surface and the removal of the produced water, finally leading to large mass transfer resistances in practical electrodes and poor power performance. In this work, we evaluate the catalytic power performance of aligned Pt nanowires grown on reduced graphene oxide (rGO) (PtNW/rGO) as cathodes in 16-cm2 single PEMFCs. The results are compared to Pt nanoparticles deposited on rGO (Pt/rGO) and commercial Pt/C nanoparticle catalysts. It is found that the scaffolding effect from the aligned Pt nanowire structure reduces the mass transfer resistance in rGO-based catalyst electrodes, and a nearly double power performance is achieved as compared with the Pt/rGO electrodes. However, although a higher mass activity was observed for PtNW/rGO in membrane electrode assembly (MEA) measurement, the power performance obtained at a large current density region is still lower than the Pt/C in PEMFCs because of the stacking effect of rGO.

The enhanced performance of carbon nanotubes (CNTs) over carbon black as a catalyst support and the outstanding catalytic activities of one-dimensional (1D) Pt nanostructures endow them big potential for applications in fuel cells. However, the research has been mainly focused on the materials, and a combination of both 1D Pt nanostructures and CNTs to fabricate practical high power performance fuel cell electrodes still remains a challenge. In this work, we demonstrate catalyst electrodes from Pt nanorods grown on aligned nitrogen doped CNTs for proton exchange membrane fuel cell (PEMFC) applications. Short Pt nanorods are grown on CNTs deposited directly on 16 cm2 carbon paper gas diffusion layers (GDLs) via plasma enhanced chemical vapour deposition (PECVD) and nitrided using active screen plasma (ASP) treatment, which are directly employed as cathodes for H2/air PEMFCs. The thin open catalyst layer effectively enhances mass transfer performance and, with a less than half of the Pt loading, 1.23 fold power density is achieved as compared with that from commercial Pt/C catalysts. A better durability is also confirmed which can be attributed to the good structure stability of nanorods and the enhancement effects from the N-CNT support.

The development of one-dimensional (1D) nanostructures for hydrocarbon oxidation reaction has attracted increasing efforts. The unique anisotropic morphology and special surface properties of 1D catalysts endow them with many advantages as compared with conventional 0D nanoparticles in proton exchange membrane fuel cells applications with liquid fuels. In this chapter, we discuss the recent progress in 1D Pt, Pt-based alloy, and non-Pt precious catalysts for this application, with a focus on the understanding of structure-catalytic property relationships in the electrooxidation of methanol, ethanol, and formic acid for potential fuel cell applications.