Preparation of Platinum Catalysts on Porous Titanium Nitride Supports by Atomic Layer Deposition and Their Catalytic Performance for Oxygen Reduction Reaction

The exploitation of high-performing stable oxygen reduction reaction (ORR) electrocatalysts is critical for energy storage and conversion technologies. The existing high- efficiency electrocatalysts applied to the ORR are mainly based on Pt and its alloys. Moreover, carrier catalysts are the most widely used in actual electrocatalysis. A suitable carrier 4 so not only improves the utilization rate of precious metals and the service life of the catalyst, but also serves as a co-catalyst to ameliorate the catalytic activity through a synergistic effect in the reaction. Therefore, research into Pt-based 41. electrocatalysts mainly focuses on the precious metal Pt and the carrier. With the aim of improving the activity and durability of Pt-based catalysts for the ORR, one-dimensional porous titanium nitride (TiN) nanotubes with a large specific surface area as well as good conductivity, electrochemical stability, and corrosion resistance were prepared in this study, and then, Pt nanoparticles were deposited on the TiN-support by atomic layer deposition (ALD). ALD is a novel and simple method for the preparation of films or nanoparticles with fine control of the thickness or size, respectively. The results of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) experiments confirmed that the Pt nanoparticles obtained by ALD (ALD-Pt/TiN) were face-centered cubic (fcc) crystals with a uniform size and were highly dispersed on the surface of TiN. X-ray spectroscopy (XPS) measurements verified that the binding energy of Pt 4f in ALD-Pt/TiN was positively shifted by 0.33 eV with respect to that of the Pt/C catalyst, indicating strong electronic interactions between the ALD-Pt nanoparticles and the TiN carriers. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) analyses revealed that ALD-Pt/TiN possessed high activity for the ORR and favorable durability. The onset potential and diffusion-limiting current density of ALD-Pt/TiN were similar to those of commercial Pt/C, while the half-wave potential was 20 mV higher than that of commercial Pt/C, indicating better electrocatalytic performance of the designed material. Furthermore, the electrocatalytic mechanism and kinetics for ALDPt/TiN were investigated by rotating ring-disc electrode (RRDE) experiments. The results suggested that the electron transfer number of the ALD-Pt/TiN catalyst was about 3.93, indicating that the ORR on the electrode was dominated by an efficient four-electron pathway. At the same time, the peroxide content was only 5%. The results of accelerated durability testing (ADT) showed that ALD-Pt/TiN had better ORR stability than Pt/C. This excellent electrocatalytic performance was probably due to the high dispersibility of the Pt nanoparticles deposited by ALD, good conductivity and corrosion resistance of TiN, and strong interactions between ALD-Pt and the TIN support. This work provides a reliable strategy for the design of new electrocatalytic materials with high activity and stability. Future research will focus on the strong interactions between ALD-Pt and the TiN carriers.