This study presents the calibration methodology of NiCr-NiSi thin-film thermocouples and evaluates their application in real-time temperature monitoring and characterization of fuel cell thermal behavior. Experimental results reveal that the Seebeck coefficients of the NiCr-NiSi thin films remain stable after multiple calibration cycles, indicating good reliability and repeatability. Furthermore, the thermocouples demonstrate an ultrafast response time of less than 15 microseconds and reach thermal equilibrium within 200 microseconds under transient thermal inputs. These characteristics enable accurate and rapid temperature measurement of fuel cell plates up to 100 °C, which is critical for maintaining the safe and efficient operation of fuel cells.

Based on the COMSOL simulation software (v.6.1), this paper systematically investigates the influence law of runner length on the velocity and pressure distribution of cathode and anode gas runners in proton exchange membrane fuel cells (PEMFCs), and experimentally verifies the measurement effect of thin-film thermocouples on the operating temperature of PEMFCs. The simulation results show that the maximum pressure of the cathode and anode increases nonlinearly with the increase in the runner length, while the velocity distribution remains stable; the shortening of the runners significantly reduces the friction loss along the flow path and optimizes the matching of the permeability of the porous medium. In addition, the NiCr/NiSi thin-film thermocouple prepared by magnetron sputtering exhibits high accuracy (Seebeck coefficient of 41.56 μV/°C) in static calibration and successfully captures the dynamic response characteristics of temperature in PEMFC operation. This study provides a theoretical basis and experimental support for the optimization of fuel cell flow channel design and temperature monitoring technology.

In this study, a novel strategy to enhance the performance of palladium (Pd)-based catalysts by doping with metal oxides (Mn₃O₄, MoO₃, and SnO) has been developed in order to overcome the limitations of its low activity and high cost in the catalytic oxidation of formaldehyde (HCHO). The novelty of this strategy lies in the fact that by precisely controlling the types and doping ratios of the metal oxides, a significant enhancement of the electrochemical performance and catalytic activity of the Pd-based catalysts was achieved, while the dependence on precious metals was reduced and the cost-effectiveness of the catalysts was improved. The effects of different metal oxide doping on the catalytic performance were systematically investigated by electrochemical characterization and catalytic activity tests. Among the prepared catalysts, Pd-Mn₃O₄ showed the most excellent performance, with an electrochemically active surface area of 20.6 m²/g and a formaldehyde oxidation reaction (FOR) current density of 3.5 mA/cm², which were 31.6% and 169.2% higher than pure Pd, respectively. In a 1000 s timed current method stability test, the limiting current density of Pd-Mn₃O₄ reached 0.48 mA/cm², which is 4.4 times higher than that of pure Pd. The excellent catalytic performance is attributed to the abundant surface hydroxyl (-OH) groups provided by Mn₃O₄, which contribute to the oxidation of formaldehyde intermediates, as well as the electronic synergistic effect between Pd and Mn₃O₄, which is manifested as a 0.4 eV downshift of the Pd 3d binding energy. In addition, the sensor evaluation showed that the Pd-Mn₃O₄-based formaldehyde sensor exhibited a high sensitivity (1.5 μA/ppm), excellent linearity (R² = 0.995), minimal long-term degradation (<7% in 30 days), and ~20-fold selectivity for formaldehyde over interfering gases (e.g., ethanol). This study provides a theoretical basis and practical material reference for the development of efficient and low-cost catalysts for formaldehyde oxidation.