Creating Bridged-H* Bond Structure for Boosting Electrocatalytic Hydrogen Evolution via Phosphorus-Doped Iridium Nanosheets.

Iridium (Ir) is recognized to have extremely high catalytic activity in the hydrogen evolution reaction (HER). However, there are still technical challenges in maximizing the utilization of Ir atoms in the catalytic reaction process through dimensional regulation strategies. Herein, an innovative strategy is utilized to fabricate porous phosphorus-doped iridium (P-Ir) with a 2D structure, specifically the reduction of 1T phase-IrO ₂ (1T-IrO ₂ ) nanosheets using phosphine gas. The optimized P-Ir achieves an overpotential of 17.2 mV (vs RHE without iR-correction) in 0.5 m H ₂ SO ₄ during the HER process, outperforming benchmark Pt/C (27.0 mV) and most reported Ir-based electrocatalysts. During the long-term stability tests, P-Ir maintains stable operation for more than 100 h at both -10 and -100 mA cm ^-2 , respectively. Moreover, the HER activity and transient potential scanning results of Ir-based phosphides prove that doping P atoms in the Ir lattice promotes the reaction kinetic rate and charge transport capacity during hydrogen evolution. Theoretical calculations reveal that P atoms doping weakens the adsorption energy of H intermediates (H*) by regulating the d-band center of the Ir sites. Simultaneously, the desorption process of H* is also facilitated by forming a special bridged-H* bond structure, eventually accelerating the HER kinetics.
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