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• A novel design is proposed for proton conducting solid oxide electrolysis cell. • Energy efficiency and stability are considered in this novel heterogeneous design. • The merits of proton-conducting materials can be taken advantage of in this design. • The drawbacks of proton-conducting materials can be circumvented in this design. The proton-conducting solid oxide electrolysis cell is a promising technology for energy storage and hydrogen production. However, because of the aggressive humid condition in the air electrode side, the stability of electrolysis cells is still a concern. In addition, the energy efficiency needs further improvement before its practical application. In this work, considering both stability and energy efficiency, a novel heterogeneous design is proposed for proton-conducting solid oxide electrolysis cells. In this heterogeneous design, the merits of proton-conducting materials can be taken advantage of and the drawbacks of proton-conducting materials can be circumvented synchronously, resulting in better stability and higher efficiency of electrolysis cells. The feasibility and advantages of the heterogeneous design are demonstrated in electrolysis cells with yttrium and zirconium co-doped barium cerate-nickel as the fuel electrode material and yttrium-doped barium zirconate as the electrolyte material by experiment and modeling. The experimental results demonstrate that compared with the conventional homogeneous design, this novel design can efficiently improve the proton conductivity of the yttrium-doped barium zirconate electrolyte (from 0.88 × 10−3 S cm−1 to 2.13 × 10−3 S cm−1 at 873 K) and slightly improve the ionic transport number of the electrolyte (from 0.941 to 0.964 at 873 K), resulting in better electrochemical performance. The electrolysis cells with this design also show good stability. Moreover, the simulation results show that the faradaic efficiency and energy efficiency of electrolysis cells are improved by applying this novel design. These impressive results demonstrate that heterogeneous design is a rational design for high-performance and efficient proton-conducting solid oxide electrolysis cell. [ABSTRACT FROM AUTHOR]

Hydrogen production by catalytic aqueous phase reforming (APR) of biomass oxygenated derivatives in relatively mild conditions is a promising way to produce hydrogen. In this work, Pt/CeO 2 -HT, Pt/La–CeO 2 -HT and PtLa/CeO 2 catalysts were synthesized by a novel photochemical reduction method and applied to the methanol APR. Extensive characterizations have proved that the mild catalyst preparation method gave it a high dispersion of Pt species and the addition of La modified the metal-support interaction. The results showed that La-modified Pt/La–CeO 2 -HT and PtLa/CeO 2 catalysts exhibited better catalytic performance than the Pt/CeO 2 -HT catalyst, among which the hydrogen yield was the highest for the surface La-modified PtLa/CeO 2 catalyst (177.7 mmol/g cat). This was mainly attributed to the surface modification of La resulted in a significant increase in the number of moderately strong basic sites and surface oxygen vacancies in the PtLa/CeO 2 catalyst. The enhancement of catalyst basicity effectively promoted the dissociation of H 2 O to produce hydroxyl groups, while a large number of surface oxygen vacancies provided more active sites for the adsorption and dissociation of H 2 O. And their synergistic behavior efficiently facilitated the water gas shift (WGS) reaction, resulting in a significant increase in hydrogen yield of methanol APR. Associated with the in situ DRIFTS analyzes and the results indicated by WGS reaction, possible promotion mechanism was proposed. [Display omitted] • Highly-dispersed APR catalysts were prepared by a novel photochemical reduction method. • The PtLa/CeO 2 catalyst exhibited the highest catalytic activity and H 2 yield (177.7 mmol/g cat). • Possible reaction mechanism of the synergistic effect on oxygen vacancies and basic sites is verified. [ABSTRACT FROM AUTHOR]

Hydrogen production by catalytic aqueous phase reforming (APR) of biomass-derived oxygenates is a promising route to produce hydrogen in a renewable way. As the typical APR catalyst, Pt/Al 2 O 3 is confronted with high methanation activity that consumes H 2 and produces undesired CH 4 during the treatment of methanol solution. In contrast, WGS reaction is the main pathway to boost H 2 generation during APR process. In this work, a series of PtFe/Al 2 O 3 catalyst with different Fe contents were prepared, characterized and tested for the methanol APR reaction. XRD, TEM, XPS and H 2 -TPR technologies were applied to study the change of physicochemical properties with the addition of iron. The restriction on methanation and promotion on WGS reaction were proved as well. With the increase of Fe content, the interaction between Pt and FeO x species have both positive and negative effects on APR reactivity while the CH 4 selectivity descending continuously from 9.25% to as low as 0.60%. Besides, the effects of reduction temperatures (250–350 °C) of Pt0.5Fe/Al 2 O 3 catalyst on APR performances were also investigated. An "Oxygen dynamic transfer cycle" between H 2 O/CO∗ and FeO x species with oxygen vacancies is proposed and verified. This indirect WGS reaction through lattice oxygen on FeO x species that boosting WGS reactivity helps improving H 2 selectivity in the gas products of methanol APR. [Display omitted] • CH 4 selectivity drops sharply from 9.25% to 0.60% with the addition of Fe on Pt/Al 2 O 3 catalyst. • The interaction between Pt and FeO x species helps boosting WGS reactivity in methanol APR. • An "Oxygen dynamic transfer cycle" is proposed to explain the acceleration of oxygen transfer. [ABSTRACT FROM AUTHOR]

Green hydrogen production from biomass oxygenated derivatives (methanol, ethanol, ethylene glycol, etc.) by low temperature aqueous phase reforming (APR) has the advantages of high hydrogen selectivity and low energy consumption. A series of Ce x Mg 1-x O 2 mixed oxide supported catalysts were synthesized by a simple citric acid combustion method. The results show that these catalysts exhibit excellent water-gas shift reaction activity and CO is rarely detected in the products, which is due to their abundant oxygen vacancies of the mixed oxide supports of the Pt/Ce x Mg 1-x O 2 catalysts. At the same time, the introduction of MgO provides more strong basic sites on the surface of mixed oxide support, and the methanol conversion and hydrogen yield show a volcano peak with the increasing number of basic sites and the hydrogen production reaches the highest (127.16 mmol) over Pt/Ce 0·5 Mg 0·5 O 2 catalyst. The mixed oxide supported Pt/Ce 0·5 Mg 0·5 O 2 catalyst enjoys the benefits of both oxygen vacancies in accelerating H 2 O adsorption/dissociation and strong basic sites in contributing to the formation of formate group (HCOO*), which improve the oxidation of CO* and APR activity. This synergistic effect is conducive to improve hydrogen yield of methanol APR and reduce CO selectivity to a minimum level. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, an asymmetric NiO–yttria-stabilized zirconia (YSZ) cathode substrate has been successfully fabricated by the phase-inversion tape casting method. 3-dimensional X-ray microscopy and subsequent analysis demonstrate that the NiO–YSZ substrates exhibit dual-layer structure: a thin sponge-like pore layer is supported on a thick finger-like macro-void layer. The electrochemical performance of the Ni–YSZ/YSZ/YSZ–LSM electrolyzer with this novel dual-layer cathode has been significantly enhanced. The electrolyzer exhibits an excellent current density of 2.3 A cm − 2 and a high H 2 production rate of 958 mL cm − 2 h − 1 at 800 °C and 1.5 V, and a polarization resistance of 0.25 Ωcm 2 at the open circuit voltage when the cathode and anode are exposed to 33 vol.% H 2 O–67 vol.% H 2 and ambient air, respectively, demonstrating that the thin sponge-like pore layer in the dual-layer cathode can provide sufficient electrochemical reaction sites for H 2 O reduction, while the thick finger-like macro-void layer can serve as the support for the electrolyzer and facilitate H 2 /H 2 O transport in the cathode, reducing the cathode polarization resistance and enhancing the cell performance. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFC), as high-temperature fuel supply systems, are regarded as one of the most adaptable technologies in terms of efficiency, flexibility, and environmental friendliness. Catalytic propane partial oxidation is recognized as an efficient gas supply method for SOFC applications. However, incombustible by-product CO 2 would decrease the purity of hydrogen, thereby reducing the power of fuel cells. Sorption-enhanced propane partial oxidation is an efficient way to adapt to SOFC operating conditions while improving hydrogen production and reducing carbon dioxide emissions. This paper introduces a cage-like porous Ce 1-x Ca x MO 3-λ (M = Co, Fe and Cu) sorbent for providing high carbon dioxide sorption capacity and improving hydrogen purity over the Ni/Al 2 O 3 catalyst. As obtained, Ce 1-x Ca x FeO 3-λ and Ni/Al 2 O 3 sorbent-catalyst performed the best, with the highest hydrogen yield up to 1654 μmol/g cat ·s which was 1055 μmol/g cat ·s higher than that of pure Ni/Al 2 O 3. The produced reforming gas is served as a fuel in the proposed SOFC system. A maximum output power density of 581 mW/cm2 was reached. This work offered a simple and viable way of combining inexpensive and robust catalyst-sorbent for sorption-enhanced propane partial oxidation in terms of efficient indirect hydrogen supply toward SOFC power generation. • Catalytic sorption-enhanced propane partial oxidation is implemented for SOFC. • Ce 1-x Ca x MO 3-λ was synthesized for CO preferential oxidation and CO 2 sorption. • Catalyst-sorbent achieved a maximum SOFC output power density of 581 mW/cm2. [ABSTRACT FROM AUTHOR]

• An efficient indirect hydrogen production-driven solid oxide fuel cell (SOFC) system is established. • Hydrogen yield is raised to 80% which is 14% higher than that using the commercial catalyst. • H 2 production and fuel cell power were improved while operating cost reduced. • The application of the catalyst brings about great advantages in capital and energy saving. Utilization of propane in solid oxide fuel cells (SOFCs) is desired for commercial applications. However, the susceptibility of conventional Ni-based anode to coking is still a technical challenge. Developing an efficient catalyst for hydrogen production through partial oxidation of propane is a feasible approach to address this issue. In fact, hydrogen production from propane partial oxidation is profoundly determined by catalyst performance, which further affects the fuel cell efficiency. In this study, a robust and efficient catalyst is developed by incorporating inexpensive TiO 2 into Ni-Co/Al 2 O 3 catalyst. The results suggested that an appropriate amount of TiO 2 in catalyst support could regulate the interaction between active metal and Al 2 O 3 support therefore inhibiting catalyst carbon deposition and sintering. Also, TiO 2 addition is conducive to the catalyst regeneration process by reducing the activation energy of oxidative decarburization. Hydrogen yield was efficiently promoted by the synthesized catalyst. Consequently, under the equivalent hydrogen (160 ml/min) produced over the catalyst, the SOFCs, with a cathode area of 15 cm2, display impressive performance (maximum power density, 404 mW/cm2) and excellent stability. Through cost-benefit analysis, the application of the synthesized catalyst is considered for great advantages in capital and energy saving. Ultimately, this work might offer a novel point of view for developing a low-cost, robust and efficient catalyst towards indirect hydrogen production for SOFCs. [ABSTRACT FROM AUTHOR]