The metal–support interaction offers electronic, compositional, and geometric effects that can enhance the catalytic activity and stability. Herein, a performance‐enhanced electrocatalyst of Pd nanoparticles loaded on a hybrid catalytic support comprised of MXene (Ti3C2Tx) and carbon nanotube (CNT) is demonstrated. Such a hybrid catalyst enhances durability and improves both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) activities compared with the Pd/C catalysts. The mass specific activity and specific activity of the Pd/Ti3C2Tx–CNT catalyst are 4.4 and 3.3 times that of Pd/C for ORR, respectively. The peak power density of a alkaline anion exchange membrane fuel cell (AAEMFC) based on the Pd/Ti3C2Tx–CNT (1:2) cathode achieves 48 mW cm−2 at 60 °C. Furthermore, Pd/Ti3C2Tx–CNT also exhibits rapid HER kinetics with a low overpotential of 158 mV at 10 mA cm−2 and a Tafel slope of 50 mV dec−1. Pd/Ti3C2Tx–CNT also provides good stability after 1000 cycles. These remarkable catalytic performances are attributed to the role of Ti3C2Tx and CNT by enhancing the catalytic activity surface area and rapid mass/charge transfer due to the synergistic effect between Pd and Ti3C2Tx–CNT.
To verify the effect of the ohmic heating on the urease activity in the soymilk, the ohmic heating methods with the different electrical field conditions (the frequency and the voltage ranging from 50 to 10 kHz and from 160 to 220 V, respectively) were employed. The results showed that if the value of the urease activity measured with the quantitative spectrophotometry method was lower than 16.8 IU, the urease activity measured with the qualitative method was negative. The urease activity of the sample ohmically heated was significantly lower than that of the sample conventionally heated (P < 0.01) at the same target temperature. It was concluded that the electrical field enhanced the urease inactivation. In addition, the inactivation kinetics of the urease in the soymilk could be described with a biphasic model during holding time at a target temperature. Thus, it was concluded that the urease in the soymilk would contain 2 isoenzymes, one is the thermolabile fraction, the other the thermostable fraction, and that the thermostable isoenzyme could not be completely inactivated when the holding time increased, whether the soymilk was cooked with the conventional method or with the ohmic heating method. Therefore, the electric field had no effect on the inactivation of the thermostable isoenzyme of the urease.
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