Complete Protection of O2-Sensitive Catalysts in Thin Films

Energy conversion schemes involving dihydrogen hold great potential for meeting sustainable energy needs, but widespread implementation cannot proceed without solutions that mitigate the cost of rare metal catalysts and the O2-instability of biological and bio-inspired replacements. Recently, thick films (>100 µm) of redox polymers were shown to prevent O2 catalyst damage, but also resulted in unnecessary catalyst load and mass transport limitations. Here, we apply novel homogeneous thin films (down to 3 µm) that provide O2-immunity while achieving highly efficient catalyst utilization. Our empirical data is explained by modeling, demonstrating that resistance to O2 inactivation can be obtained for non-limiting periods of time when the optimal thickness for catalyst utilization and current generation is achieved, even when using highly fragile catalysts such as the enzyme hydrogenase. We show that different protection mechanisms operate depending on matrix dimensions and intrinsic catalyst properties, and...