Ultra-Low Loading Pseudo-Single-Crystal Mesoporous PtPd Catalysts for High-Performance Hydrogen Gas Batteries

Rechargeable hydrogen gas batteries show a great promise for large-scale energy storage due to their high safety, environmental friendliness, high efficiency and long-cycle life. However, the costly catalysts at the anode for hydrogen oxidation/evolution reactions (HOR/HER) hinder the practicability. Here, we report a pseudo-single-crystal mesoporous (PSCM) PtPd catalyst with high HOR/HER bifunctional activities for high-performance hydrogen gas batteries. It exhibits an outstanding HOR activity with a kinetic current density of 3.10 A mg^-1 and an HER overpotential of 34.8 mV at 10 mA cm^-2, outperforming commercial Pt/C (0.42 A mg^-1, 79.3 mV). When assembling Ni-H₂ battery with a low PSCM-PtPd catalyst loading of ∼45 µg cm^-2, it displays a high energy efficiency of ∼85% and cycling stability of >1000 cycles. Even at an ultra-low catalyst loading of ∼10 µg cm^-2, the Ni-H₂ (PSCM-PtPd) battery still exhibits an energy density of ~135 Wh kg^-1 and durability of >1000 cycles with a cell cost of ~105 $ kWh^-1, much better than that of Pt/C-based battery (>700 $ kWh^-1). We demonstrate that the superior activity of the PSCM-PtPd catalyst originates from the charge transfer from Pd to Pt and lattice distortion caused by Pd incorporation, and the enhanced stability is attributed to its fewer grain boundaries and stable attachment to the electrode. This work offers a promising pathway toward designing cost-effective and scalable energy storage systems.