Evaluation of the Nickel Titanate-Modified Pt Nanostructured Catalyst for the ORR in Alkaline Media

Abstract

The electrocatalytic performance of novel Pt-NiTiO 3 /C catalyst for the oxygen reduction reaction (ORR) is investigated for the first time. The cathode has been synthesized in a two-step procedure. Firstly, the NiTiO 3 co-catalyst is obtained via a wet-chemical method. Then, 20% Pt-NiTiO 3 /C electrocatalysts (Pt:NiTiO 3 ratio of 1:1 at. %) is prepared by irradiating a mixture of NiTiO 3 , Vulcan and Pt precursor for 4 min in a microwave apparatus. As a reference, a 20% Pt/C catalyst has been synthesized by the same procedure. XRD analysis confirmed a crystalline NiTiO 3 with particle size between 25-40 nm. It also indicates the formation of nanostructured Pt-NiTiO 3 /C having a Pt particle size of less than 2 nm. TEM results show the formation of homogenously dispersed Pt nanoparticles, with particle size of 2.3 nm. The linear scan voltammograms show a performance for the ORR of Pt-NiTiO 3 /C as high as that of Pt/C in KOH. The results suggest that the reaction proceeds following a four-electron transfer mechanism. Moreover, the mass and specific activities of Pt-NiTiO 3 /C are the same as those of Pt/C, demonstrating good performance with less Pt. Furthermore, ORR selectivity tests show an enhanced tolerance of Pt-NiTiO 3 /C to 0. Polymer Electrolyte Membrane (PEMFCs) and Direct Alcohol Fuel Cells (DAFCs) are energy-producing devices with high conversion efficiency and zero or very low emission of greenhouse gases. 1-2Due to the feasibility of using H 2 as sustainable fuel or the alternative use of low-molecular weight liquid fuels with high energy density (for example CH 3 OH and C 2 H 5 OH), fuel cell systems have called the attention of research groups worldwide.1-5 Because of these energetic advantages compared to traditional heat engines, PEMFCs and DAFCs are promising as power sources for transportation, as well as portable and stationary applications. [3][4][5] Over the last decades, mostly acid membranes have been used during the development of PEM fuel cells. 6 However, recent advances in the synthesis of chemically stable anion-exchange membranes have open the opportunity for the development of Alkaline Fuel Cells (AFCs) fueled with H 2 or organic molecules (A-PEMFCs and ADAFCs, respectively). [7][8][9][10] AFCs are also of technical interest because their atmosphere is less corrosive than the operating conditions found inside PEM fuel cells, theoretically ensuring a longer life-cycle. 11-15Even more, the kinetics of the cathode reaction is faster in alkaline media than the analogous reaction in acid environment. 10,16,17 Nevertheless, the use of noble metals is highly relevant in the progress of A-PEMFCs and A-DAFCs, where electrocatalyst based on Pt are still widely used. 10,[16][17][18][19][20][21] This is particularly important in the case of the ORR, several orders of magnitude slower than the hydrogen oxidation reaction. In order to reduce the costs of cathode electrocatalysts, the amount of noble metal must be decreased, yet sustaining a high catalytic activity for the ORR. In addition to suc...

Recent Advances in Electrocatalysts for Proton Exchange Membrane Fuel Cells and Alkaline Membrane Fuel Cells

“…The recently reported noncarbon-supported Pt catalysts have improved stability but require more investigation. [193][194][195][196][197][198] Meanwhile, atomically dispersed Pt catalysts have attracted more attention due to nearly 100% utilization efficiency, which can minimize the Pt loading in fuel cells. [199] Liu et al [200] and Li et al [201] found that N-doped carbon-supported Pt single atom catalyst exhibited significantly higher ORR activity compared to the conventional Pt/C due to the synergistic effect between Pt and N atoms.…”

High-throughput, combinatorial synthesis of multimetallic nanoclusters

“…4C), slightly smaller Tafel slopes for the MMNCs (32 and 31 mV/decade) were measured, as compared with Pt (37 mV/decade), indicating a similar reaction mechanism in ORR. We also compared our result with the literature data, and our MMNCs are still among best-performing catalysts (SI Appendix, Table S3) (43)(44)(45)(46)(47).…”

Advanced Trifunctional Electrocatalysis with Cu-, N-, S-Doped Defect-Rich Porous Carbon for Rechargeable Zn–Air Batteries and Self-Driven Water Splitting

“…Green and sustainable energy has attracted worldwide attention but the biggest obstacle in adoption and implementation is the efficient conversion and rapid storage of energy. − It is generally believed that fuel cells, metal–air batteries, and water splitting are promising energy storage and conversion technologies, which can be a paradigm shift in the adoption and usage of renewable energy compared to fossil fuels. , The oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are two key reactions in fuel cells and metal–air batteries, while the hydrogen evolution reaction (HER) and OER play a significant role in water splitting. − Typically, the ORR, OER, and HER reactions use noble metal-based catalysts to improve the reaction rate or optimize the reaction process. For example, Pt-based catalysts are highly effective for ORR and HER catalysis, and Ru- or Ir-based catalysts can be well utilized for the OER. , However, noble metal scarcity, coupled with their lack of multifunctionality in abovementioned three reactions (i.e., Pt cannot be used for both ORR and OER), makes it difficult to develop the large-scale adoption or industrialization of these energy storage technologies . Therefore, it would be greatly advantageous and significant to design multifunctional and low-cost (noble metal-free) catalysts with high activity. , …”