Atomic layer deposition of Pt@CsH2PO4 for the cathodes of solid acid fuel cells

Abstract

Atomic layer deposition (ALD) has been used to apply continuous Pt films on powders of the solid acid CsH 2 PO 4 (CDP), in turn, used in the preparation of cathodes in solid acid fuel cells (SAFCs).The film deposition was carried out at 150 °C using trimethyl(methylcyclopentadienyl)platinum (MeCpPtMe 3 ) as the Pt source and ozone as the reactant for ligand removal. Chemical analysis showed a Pt growth rate of 0.09 ± 0.01 wt%/cycle subsequent to an initial nucleation delay of 84 ± 20 cycles. Electron microscopy revealed the contiguous nature of the films prepared using 200 or more cycles. The cathode overpotential (0.48 ± 0.02 V at a current density of 200 mA/cm 2 ) was independent of Pt deposition amount beyond the minimum required to achieve these continuous films. The cell electrochemical characteristics were moreover extremely stable with time, with the cathode overpotentials increasing by no more than 10 mV over a 100 h period of measurement. Thus, ALD holds promise as an effective tool in the preparation of SAFC cathodes with high activity and excellent stability.

Role of Reaction Intermediate Diffusion on the Performance of Platinum Electrodes in Solid Acid Fuel Cells

“…Platinum (Pt) is the most common electrocatalyst for SAFCs due to its high activity and stability. For SAFCs, various deposition and fabrication methods have been investigated, resulting in different electrocatalyst microstructures and electrode architectures [7][8][9][10][11][12][13][14][15]. The deposition methods included metal-precursor impregnation, metal-organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD) and direct current magnetron sputtering (dcMS), and these methods were utilized on the current collector as well as the electrolyte particles.…”

“…In particular, Pt composite electrodes have demonstrated power densities of 415 mW cm −2 and performance degradation of just 110 µV h −1 at 200 mA cm −2 . [12][13][14] Nevertheless, the performance was achieved with a high Pt loading of greater than 1 mg cm −2 per electrode, indicating a broad research field to enhance SAFCs in terms of power output at reduced Pt loading, hence a lower cost. In other types of fuel cells, the electrode microstructure of Pt and other electrocatalysts has been modified using additives, electrodeposition and nanocages [16][17][18].…”

“…The second one is only diffusion-controlled, whereas the mixed-controlled region is limited by interfacial effects and the diffusion process. The rate-limiting reaction of an SAFC is the oxygen reduction reaction (ORR) at the cathode [14,20]. The reaction mechanism is slower overall and consists of a four-electron process that can be described by an associative and a dissociative mechanism [21,22].…”

“…The reaction mechanism is slower overall and consists of a four-electron process that can be described by an associative and a dissociative mechanism [21,22]. Additionally, in the case of the ORR, the contribution of the triple-phase boundary as well as the diffusion of reaction intermediates through or on the surface of the catalyst still remain unclear [10,14]. Lim et al proposed, for Pt-coated electrolyte particles, that the catalytic activity of the cathode is caused by a diffusion of hydrogen through the electrocatalyst [14].…”

Atomik Katman Biriktirme Tekniğine Genel Bakış: Zno, Tio2 Ve Al2o3 Filmlerin Üretimi

“…Son zamanlarda yapılan bilimsel çalışmalar ve teknolojik ürünler değerlendirildiğinde, optoelektronik, enerji dönüşümü, nano-boyutlu medikal malzemeler ve katalizör malzemeler gibi uygulama alanlarındaki teknolojilerin nano-boyutlu malzeme üretimine ihtiyaç duyduğu görülmektedir. Bu alanlarda üretilen yüksek dielektrik sabitli transistörler [1][2][3][4][5], bellek aygıtları [6][7][8], gaz difüzyon bariyerleri [9][10][11], organik ışık yayan diyotlar (OLED'ler) [12][13][14], esnek elektronik aygıtlar [15], yakıt hücreleri [16][17][18], sensörler [19][20][21], güneş panelleri [22][23][24][25], biyoelektronik cihazlar, implantlar, ilaç sistemleri [26][27][28][29], su ayrıştırma [30][31][32][33] gibi pek çok teknoloji ince film üretim tekniklerinin kullanmasını gerektirmektedir. Magnetron sputtering [34][35][36], moleküler ışın epitaksi (MBE) [37], Spray-pyrolysis [38], sol-gel [39,40], kimyasal buhar biriktirme (CVD) [41,42] ve atomik katman biriktirme (ALD) [43]…”