Investigations on a platinum catalyzed membrane for electrolysis step of copper‐chlorine thermochemical cycle for hydrogen production

Abstract

Considering the low temperature demand (550 C maximum) and high efficiency (43%), Cu-Cl thermochemical water splitting cycle has immense potential as a futuristic scalable hydrogen generation process. CuCl/HCl electrolysis is the crucial hydrogen generation step in the Cu-Cl thermochemical cycle. The efficiency of this electrolysis process is highly dependent on the performance of the membrane electrode assembly (MEA) employed. To explore the suitability of the platinized membrane for this step, in this study, we have investigated a Pt/Nafion-117 MEA prepared by in-situ impregnation-reduction method for CuCl/HCl electrolysis. A single-cell PEM-type electrolyser (4 cm 2 active area) consisting of serpentine channels (2 cm × 2 cm) grooved in graphite flow field plates was designed and fabricated to carry out the CuCl/HCl electrolysis. Platinum electrocatalyst was deposited on Nafion-117 membrane on the cathodic side by reduction of hexachloroplatinic acid (H 2 PtCl 6) with sodium borohydride (NaBH 4) by the impregnation-reduction method which served as the MEA. Monodispersed nanocrystalline Pt particles formed a 30 μm thick electrocatalyst layer on the membrane. Pt/Nafion-117 MEA was found to be effective for CuCl /HCl electrolysis. In a PEM-type electrolyser with Ar-purged 0.2 M CuCl in 2 M HCl solution as anolyte flowing at 8.8 mLmin −1 , a current density of 100 mA cm −2 was achieved at a cell voltage of 1 V. However, undesired Cu-crossover could be noticed from anode to cathode side during operation.

Investigations on CuCl/HCl Electrolysis Using a Pt/C Electrocatalyst-based Membrane Electrode Assembly

“…Fabrication of electrolyser.-The CuCl/HCl electrolyser is based on a PEM electrolyser design as discussed earlier. 48 A schematic of the design is shown in Fig. 2a.…”

“…thermodynamic and kinetic issues, understanding fundamental reaction steps, optimization of operating parameters, solving material issues in high acidic environments (membrane, catalyst, cell components etc. ), achieving high efficiencies to decrease electrical demand, designing electrolyzers, minimizing side reactions and undesired crossovers etc The z E-mail: atinmb@barc.gov.in; atinmb@gmail.com scientific advances have been recently well reviewed in the articles by Li et al 47 and Farsi et al 43 CuCl/HCl electrolysers uses the advanced concept of membrane electrode assembly (MEA) with cathode and anode flow field plates on either side as discussed elsewhere 48 and shown in Fig. 1b.…”

“…43,47,[49][50][51][52][53][54] In our earlier study, we had employed a platinized Nafion membrane as MEA with electrocatalyst coated only on the cathode side. 48 In this study we prepare Pt/C electrocatalyst with varied Pt loadings and compare their electrochemical surface area (ECSA). The highest ECSA electrocatalyst composition is then employed to fabricate the MEA with catalyst only on the cathode side.…”

Studies on Reaction Products, Byproducts, and Intermediates in Thermal Steps of the Cu–Cl Thermochemical Cycle for Hydrogen Generation

“…More than 200 thermochemical cycles have been devised based on Hess’s law of thermodynamics . Among these, iodine–sulfur (I–S), − hybrid sulfur, and copper–chlorine − thermochemical processes are found to be efficient and promising for large-scale sustainable hydrogen production. The maximum operation temperature of the Cu–Cl thermochemical cycle ( T max = 530 °C) is much lower as compared to sulfur-based cycles ( T max = 850 °C), thus offering advantages in the selection of materials of construction, and also enhances the practicability for the Cu–Cl process to be coupled with a solar energy source .…”

A review of alkaline solid polymer membrane in the application of AEM electrolyzer: Materials and characterization

“…Besides, without any delay in fuel processing, hydrogen can be generated directly via the electrolyzer unit. It can be placed anywhere, not like a solar cell requiring areas of high sunlight intensity 21,22 . In addition, an electrolyzer unit can be integrated with another power source system in various applications such as stationary, portable, and transportation to provide reliable energy supplies over a long period.…”