Analyzing Pd Metallosurfactant derived single atom catalyst for Biofouling Mitigation and oxygen reduction reaction in microbial fuel cell

Abstract

Cathode biofouling remains a major challenge to the efficiency and long-term stability of membrane-less single-chamber microbial fuel cells (SCMFCs). Herein, we report the synthesis of Pd single-atom and ultrasmall Pd nanocluster-decorated N-doped mesoporous carbon catalyst (PdNC@Pd-SAC) via a wet impregnation-assisted pyrolysis-deposition route. Pd-DDAB metallosurfactant acted as a single-source precursor for Pd, N, and C, while amine-functionalized mesoporous silica nanoparticles (MSiNs) served as a structural template to direct the formation of a stable palladium-anchored mesoporous carbon framework. During high-temperature pyrolysis, the decomposition of Pd-DDAB generated volatile intermediates that transformed into carbon residues confined within the silica meso-channels, facilitated by the synergistic interaction of the amphiphilic surfactant moiety and Pd active centers forming micellar assemblies. Morphological analysis revealed the coexistence of atomically dispersed Pd sites and ultrasmall Pd nanoclusters. The synergistic electronic and spillover effects of these dual active sites significantly enhanced the four-electron ORR pathway while mitigating cathode biofouling. PdNC@Pd-SAC achieved a half-wave potential of 0.82 V vs RHE and a diffusion-limited current density of 4.82 mA cm⁻², comparable to Pt/C, along with superior durability and resistance to Pd agglomeration. In SCMFCs, it delivered 582 mW m⁻² power density i.e. 1700 percent higher than bare CC, and maintains stable output voltage over one month operation. PdNC@Pd-SAC directly interacts with bacterial cell-membrane, penetrates intracellularly, disrupts membrane integrity, causes cellular content release, and effectively prevents cathode biofouling.