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Over the past decades, the design of active catalysts has been the subject of intense research efforts. However, there has been significantly less deliberate emphasis on rationally designing a catalyst system with a prolonged stability. A major obstacle comes from the ambiguity behind how catalyst degrades. Several degradation mechanisms are proposed in literature, but with a lack of systematic studies, the causal relations between degradation and those proposed mechanisms remain ambiguous. Here, a systematic study of a catalyst system comprising of small particles and single atoms of Pt sandwiched between graphene layers, GR/Pt/GR, is studied to unravel the degradation mechanism of the studied electrocatalyst for oxygen reduction reaction(ORR). Catalyst suffers from atomic dissolution under ORR harsh acidic and oxidizing operation voltages. Single atoms trapped in point defects within the top graphene layer on their way hopping through toward the surface of GR/Pt/GR architecture. Trapping mechanism renders individual Pt atoms as single atom catalyst sites catalyzing ORR for thousands of cycles before washed away in the electrolyte. The GR/Pt/GR catalysts also compare favorably to state‐of‐the‐art commercial Pt/C catalysts and demonstrates a rational design of a hybrid nanoarchitecture with a prolonged stability for thousands of operation cycles. [ABSTRACT FROM AUTHOR]

Abstract: With an aim to develop a proton-exchange-membrane fuel cell (PEMFC) with improved water management, catalyst-coated membranes based upon Nafion 212 membrane with electrodes of dual-layer structure which consist of one hydrophilic layer of Pt/C+Nafion and one hydrophobic layer of Pt/C+PTFE arranged in a proper order, is specifically designed and successfully fabricated by a facile high-temperature spray deposition technique. Dual-layer structured anode and cathode are separately evaluated by electrochemical performance in single cells. Effect of relative thickness of the dual layers in the electrode on the cell performance is investigated. No improvement in cell performance is observed by adopting the dual-layer structure for the anode as compared to conventional anode with single hydrophilic catalyst layer. However, better cell performance is observed for the cell with dual-layer structured cathode, and the optimal cell reaches a peak power density of about 800mWcm−2 at 50°C with humidified hydrogen and oxygen as fuel and oxidant respectively. [Copyright &y& Elsevier]

The potential to use ethanol as a fuel places solid oxide fuel cells (SOFCs) as a sustainable technology for clean energy delivery because of the renewable features of ethanol versus hydrogen. In this work, we developed a new class of anode catalyst exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 (Ni+BZCY) with a water storage capability to overcome the persistent problem of carbon deposition. Ni+BZCY performed very well in catalytic efficiency, water storage capability and coking resistance tests. A stable and high power output was well maintained with a peak power density of 750 mW cm−2 at 750 °C. The SOFC with the new robust anode performed for seven days without any sign of performance decay, whereas SOFCs with conventional anodes failed in less than 2 h because of significant carbon deposition. Our findings indicate the potential applications of these water storage cermets as catalysts in hydrocarbon reforming and as anodes for SOFCs that operate directly on hydrocarbons. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts with low cost is critical for the wide‐spread application of sustainable and renewable energy conversion technologies. Single‐atom catalysts (SACs) have attracted considerable attention owing to their high catalytic activity, selectivity, and stability. However, the high surface energy of the single atoms often results in an extremely low loading of metal atom catalysts with limited mass activity. In this context, densely populated SACs are more promising for practical applications due to their high active surface area and mass activity. Herein, the recent research progress of high loading (≥5 wt%) SACs for different electrocatalytic applications is summarized. An overview of various synthesis and characterization strategies of SACs is presented in this review. The influence of appropriate substrates on the preparation of high metal loading SACs is also discussed. In addition, this review provides valuable insights into the current challenges and future opportunities in the field of single‐atom catalysts. [ABSTRACT FROM AUTHOR]

Nickel-based cermet anode-supported protonic ceramic fuel cells (PCFCs) show great potential for direct utilization of ammonia. However, the insufficient activity of anode and the deterioration of anode activity/durability caused by the undesired interaction between nickel and ammonia greatly limit the application. Here, we report tubular PCFCs embedded with a catalytic iron layer. Such cells show peak power densities of 1.507 W cm-2 and 1.078 W cm-2 at 700 °C when using H 2 and NH 3 as fuel, respectively, which are the highest tubular PCFC performance so far ever reported. In addition, the stability of cells with the catalyst layer has been dramatically enhanced when compared with that of cells without the catalyst layer. The enhancement of activity and durability is attributed to the catalytic activity of iron for ammonia decomposition, through which the direct contact between nickel and ammonia has been minimized and the anode structure has therefore been protected. [Display omitted] • A robust tubular cell has been fabricated via a phase inversion process. • The cell delivers excellent peak power densities of 1.507 W cm-2 on H 2 , and 1.078 W cm-2 on NH 3 at 700 °C. • The cell durability is greatly enhanced when integrated with a catalytic Fe layer. • A DFT study indicates that the Fe layer can effectively decompose the NH 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu+ species are stabilized over Cu(I)-O-Co interfaces. • Cu(I)-O-Co interface suppresses OH group formation and enhances water resistance. • Water over the Cu(I)-O-Co interface can alter the reaction mechanism. • CO coupling with adsorbed O 2 is the rate determining step under humid condition. The development of low-temperature and water-resistant heterogeneous catalysts without noble metals is vital in the effective treatment of atmospheric pollutants in practical application. Herein, we report that Cu(I)-O-Co interfaces of ultrafine CuO x on Co 3 O 4 prepared by co-precipitation exhibit promising low-temperature activity and good water resistance. Experiment results together with density functional theory (DFT) calculations not only verify that Cu+ species are stabilized over Cu(I)-O-Co interfaces because of the strong interaction between Cu 2 O 1 and Co 3 O 4 , but also demonstrate that the Cu(I)-O-Co interface facilitates oxygen species activation for promoting catalytic oxidation and reduces the accumulation of hydroxyl and bicarbonate species on the surface of CuO x /Co 3 O 4. DFT calculations also reveal that the CO oxidation rate-limiting step via the dissociation pathway under dry conditions is the Co-OO-Cu species dissociation while the CO coupling with the adsorbed O 2 becomes the rate determining step for CO oxidation through the direct pathway over Cu(I)-O-Co interface under humid conditions. Further, the CuO x /Co 3 O 4 catalyst also exhibits superior and stable catalytic activity for toluene oxidation, comparable with partial supported noble metal catalysts (T 90 = 190 °C). The present work gives a useful strategy for the rational design of low-temperature and water-resistant non-precious-based catalysts to be applicable in CO and toluene removal in practical applications. [ABSTRACT FROM AUTHOR]