A symmetric direct ammonia fuel cell enabled with poisoning-tolerant PtCo/C electrodes

The ammonia oxidation reaction (AOR) is a key anodic process in low-temperature direct ammonia fuel cells (DAFCs), and its catalytic efficiency directly determines the energy conversion performance. Although a well-established structure-activity relationship exists between Pt-based materials and AOR behavior, pure Pt still suffers from *N intermediate poisoning and high precious metal loading. Herein, we report a nanostructured PtCo solid-solution catalyst synthesized via a two-step pyrolysis strategy. Structural characterization studies reveal that the incorporation of Co atoms into the Pt face-centered cubic lattice induces lattice contraction and a negative shift in the Pt 4f binding energy, which weakens the Pt-N bond strength. The optimized PtCo/C-3 catalyst exhibits a low onset potential of 0.50 V vs. RHE and a peak current density of 79.3 mA cm^-2 for alkaline AOR, while retaining approximately 90% of its initial activity after 400 cycles. In a DAFC test, a symmetric cell employing the PtCo/C-3 catalyst as both the anode and cathode delivers an open-circuit voltage of 0.56 V and a maximum power density of 47.9 mW cm^-2 at 90 °C. This work reveals a viable route to modulate the electronic structure of Pt via trace 3d-metal alloying, simultaneously mitigating poisoning and enhancing intrinsic AOR activity, offering a new paradigm for poisoning-tolerant anode design for DAFCs.