Mechanistic studies revealed that the optimized deposition of CoPOM using the PEI linker translates directly into improved efficiency of the transfer of photogenerated oxidizing equivalents (holes) to water molecules and thus to enhanced oxygen evolution. On the other hand, the charge separation efficiency in triad photoanodes was largely unaffected by the CoPOM loading, and remained rather low (below 10% at moderate bias potentials), suggesting that primary recombination is a key performance bottleneck in triad photoanodes. Importantly, we also show that the PEI linker is effectively stabilized in the presence of the CoPOM catalyst that efficiently extracts the holes from PEI, preventing thus its oxidative degradation that takes place in the absence of CoPOM. This work thus highlights the importance of careful design of multi-component photoelectrocatalytic systems, and provides a simple protocol for effective immobilization of POM-based catalysts into soft matter-based photoelectrocatalytic architectures for light-driven water oxidation.