Palladium hydride (PdH x ) metallenes are efficient electrocatalysts for the oxygen reduction reaction (ORR) due to their high atomic utilization and optimized oxygen binding energies modulated by interstitial hydrogen. However, their practical application is restricted by the highly unstable nature of interstitial hydrogen at working temperatures around 353 K. Here, we report that the use of Mn effectively locks hydrogen atoms within the Pd metallenes lattice, resulting in high alkaline ORR performance across a temperature range of 303–353 K. In contrast, the ORR activity of PdH x metallenes declines sharply with increasing temperature. At 353 K, the mass activity of PdMnH x metallenes at 0.95 V reaches 1.41 A mg − 1 , which is 14.1 times higher than that of PdH x metallenes. Multiple spectroscopic analyses and theoretical calculations reveal that strong electronic interactions within the immiscible Pd-Mn alloy are critical for locking interstitial hydrogen, thereby enhancing the ORR activity under high temperatures.
Rational control of the components of noble metal alloys is paramount for achieving satisfactory electrocatalytic performances. Though transition metals are commonly used to modify noble metals, many potential elements remain to be explored. Here, we interstitially modulate hydrogen atoms into RhPd nanoparticles to boost the alkaline hydrogen evolution reaction (HER). The obtained stable RhPd-H nanoparticles exhibit pronounced alkaline HER activity with a small overpotential of 36.6 mV at 10 mA cm–2 and a low Tafel slope of 35.3 mV dec–1. The surface electronic state, bond distance, and coordination number of the Rh and Pd atoms are significantly influenced by the presence of interstitial hydrogen atoms. These modifications give RhPd-H nanoparticles a desirable hydrogen adsorption free energy, thus accelerating the hydrogen gas production. We further demonstrate that the interstitial hydrogen atom modulation strategy to improve the HER activity is universal for other Pd-based alloy nanostructures. This work presents a powerful strategy for designing efficient electrocatalysts for the HER and beyond.
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