New calcium-doping strategy surpasses platinum catalysts in hydrogen fuel cells

New calcium-doping strategy surpasses platinum catalysts in hydrogen fuel cells

by Riko Seibo

Sendai, Japan (SPX) Feb 12, 2024

In an innovative stride towards enhancing the efficiency of hydrogen fuel cells, a research team has unveiled a novel method that significantly improves the electrochemical surface area (ECSA) of a calcium-doped perovskite, La0.6Ca0.4MnO3 (LCMO64). This development is poised to address a notable challenge in leveraging perovskite oxides as effective electrocatalysts in hydrogen fuel cells, a promising direction for sustainable energy technology.

Published in the journal Advanced Materials on November 29, 2023, the study delves into the intricacies of perovskite oxides, materials celebrated for their diverse and compelling properties. These oxides are particularly esteemed for their high intrinsic activities, positioning them as a viable alternative to the traditionally used noble metal catalysts in catalyzing the oxygen reduction reaction (ORR), a critical process in the operation of hydrogen fuel cells. Despite their potential, the practical application of perovskite oxides has been curtailed by their limited electrical conductivity and low specific surface area.

The breakthrough method, as elaborated by Hao Li, Associate Professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR) and the corresponding author of the study, involves an electrochemically induced calcium-leaching process. This process not only augments the ECSA in LCMO64 but also marks a significant improvement in the material’s electrocatalytic ORR performance. “The activated, calcium-deficient LCMO64 demonstrated an ECSA approximately 33.84% higher than that of unactivated materials, showcasing superior electrocatalytic ORR performance-surpassing the benchmark commercial Pt/C catalyst in an alkaline solution,” Li stated.

The research team’s approach included theoretical analysis, electrochemical surface state probing, and pH-dependent microkinetic modeling to establish the material’s benchmarks. The findings underscored that the catalyst reaches the Sabatier optimum for alkaline ORR, indicating an optimal balance between the adsorption and desorption of reactants and products on the catalyst’s surface, a crucial criterion for efficient catalysis.

This study is notable for being the first to utilize calcium (Ca) doping as a strategy to overcome the inherent limitations of low conductivity and surface area in perovskite oxides. The observed phenomenon of Ca leaching under ORR conditions leads to increased surface roughness and, consequently, an expanded available surface area for ORR, enhancing the catalyst’s overall performance.

Li further emphasized the broader impact of their work, stating, “Finding low-cost and effective electrocatalysts for the ORR in hydrogen fuel cells has been a significant challenge. Our work not only addresses this challenge but also offers a novel strategy for enhancing the electrocatalytic performance of perovskite oxides.” This advancement heralds a significant leap towards the widespread adoption of hydrogen fuel cell technology, promising a future where sustainable and efficient energy solutions are more accessible.

Research Report:Cation-Deficient Perovskites Greatly Enhance the Electrocatalytic Activity for Oxygen Reduction Reaction