Tuning the Adsorption of H and OH on Ruthenium Aerogel to Boost the Alkaline Hydrogen Evolution

Ruthenium (Ru) is an ideal alternative to platinum for the alkaline hydrogen evolution reaction (HER) due to its exceptional catalytic performance. However, during the reaction, the excessively strong adsorption of proton (H) and hydroxyl (OH) species on Ru significantly limits its alkaline HER activity. Herein, we enhanced the alkaline HER performance of Ru by modulating its crystalline phase structure and incorporating a low dosage of Cr ions. The synthesized Cr_0.033Ru_{0.967 fcc/hcp} aerogel exhibits a lower overpotential of only 14 mV at 10 mA cm^-2, outperforming Ru aerogels (Ru_fcc and Ru_hcp) and commercial Pt/C catalysts. Moreover, Cr_0.033Ru_{0.967 fcc/hcp} aerogel demonstrates a remarkable stability at 500 mA cm^-2, sustaining continuous operation for 800 h. Experimental results, combined with theoretical calculations, reveal that the heterogeneous phase interfaces in the CrRu_fcc/hcp aerogel effectively weaken the strong adsorption of H at Ru sites. Additionally, with their high affinity for OH species, Cr ions facilitate the removal of OH from adjacent Ru sites. Furthermore, Cr ion incorporation modifies the local electronic structure of Ru, further reducing its OH adsorption energy. This work highlights a synergistic approach to improving catalytic performance and offers a novel strategy for designing highly efficient and durable alkaline HER catalysts.