This work investigates the transient performance and stability of CO₂/H₂O co-electrolysis in an air-free environment using a flat-tube solid oxide electrolysis cell (SOEC) stack. The results showed that the transient behavior of the stack with and without blowing gas into the air electrode is almost the same. With a current density of 0.67A·cm^-2 @750 °C, the stack operated for over 200 h under co-electrolysis conditions without air blowing, and the voltage drop rate of the stack was approximately 0.203%/100 hours. Microstructure analyses revealed a significant loss of nickel particles and an apparent formation of an insulating phase strontium chromate (SrCrO₄) on the surface of the current collection layer of the air electrode, which are identified as key factors contributing to the performance degradation of the stack. This study provides a reference for development of efficient fuel preparation technology based on SOEC stack in airless environments.

Alloying transition metals with Pt is an effective strategy for optimizing Pt-based catalysts toward the oxygen reduction reaction (ORR). Atomic ordered intermetallic compounds (IMC) provide unique electronic and geometrical effects as well as stronger intermetallic interactions due to the ordered arrangement of metal atoms, thus exhibiting superior electrocatalytic activity and durability. However, quantitatively analyzing the ordering degree of IMC and exploring the correlation between the ordering degree and ORR activity remains extremely challenging. Herein, a series of ternary Pt₂NiCo intermetallic catalysts (o-Pt₂NiCo) with different ordering degree were synthesized by annealing temperature modulation. Among them, the o-Pt₂NiCo which annealed at 800 °C for two hours exhibits the highest ordering degree and the optimal ORR activity, which the mass activity of o-Pt₂NiCo is 1.8 times and 2.8 times higher than that of disordered Pt₂NiCo alloy and Pt/C. Furthermore, the o-Pt₂NiCo still maintains 70.8% mass activity after 30,000 potential cycles. Additionally, the ORR activity test results for Pt₂NiCo IMC with different ordering degree also provide a positive correlation between the ordering degree and ORR activity. This work provides a prospective design direction for ternary Pt-based electrocatalysts.

Nitric oxide (NO), which generally originates from vehicle exhaust and industrial flue gases, is one of the most serious air pollutants. In this case, the electrochemical NO reduction reaction (NORR) not only removes the atmospheric pollutant NO but also produces valuable ammonia (NH₃). Hence, through the synthesis and modification of Fe₃C nanocrystal catalysts, the as-obtained optimal sample of Fe₃C/C-900 was adopted as the NORR catalyst at ambient conditions. As a result, the Fe₃C/C-900 catalyst showed an NH₃ Faraday efficiency of 76.5% and an NH₃ yield rate of 177.5 μmol·h^-1·cm^-2 at the working potentials of -0.8 and -1.2 V versus reversible hydrogen electrode (vs. RHE), respectively. And it delivered a stable NORR activity during the electrolysis. Moreover, we attribute the high NORR properties of Fe₃C/C-900 to two aspects: one is the enhanced intrinsic activity of Fe₃C nanocrystals, including the lowering of the energy barrier of rate-limiting step (*NOH→*N) and the inhibition of hydrogen evolution; on the other hand, the favorable dispersion of active components, the effective adsorption of gaseous NO, and the release of liquid NH₃ products facilitated by the porous carbon substrate.

A unitized regenerative fuel cell (URFC) is a device that may function reversibly as either a fuel cell (FC) or water electrolysis (WE). An important component of this device is the Membrane electrode assembly (MEA). Therefore, this study aimed to compare the performance outcomes of MEA using electrodes with single and three catalyst layers. This study measured Electrochemical Surface Area (ECSA), Electrochemical Impedance Spectroscopy (EIS), X-ray Diffraction analysis (XRD), and X-ray Fluorescence (XRF). Furthermore, the round-trip efficiency (RTE) of the MEA, as well as the performance in FC and WE mode, was measured. In comparison, The ECSA values of Pt-Ru/C and Pt/C with three catalyst layers were higher than the single catalyst layer. This result was supported by electrode characterization data for XRD and XRF. The respective electrical conductivity values of Pt-Ru/C and Pt/C with three catalyst layers are also higher than the single catalyst layer, and the performance of URFC using MEA with three catalyst layers has the highest value of RTE among the MEA performances of URFC, which is 100% at a current density of 4 mA·cm^-2.