The development of cost-effective and high-performance electrocatalysts for water oxidation has attracted intense research interest. It was reported recently that the interface between the amorphous and crystalline phases plays a significant role in the electrocatalytic activity of transition metal compounds. It was reckoned therefore that an increase in the density of the crystalline–amorphous phase boundary would enhance the electrochemical water oxidation on the catalyst. In this work we develop a new and facile strategy for inducing high density crystalline–amorphous phase boundaries via selective fluorination surface doping. This resulted in excellent characteristics of the engineered material for electrochemical water splitting. An initial computational simulation is carried out to design the crystalline–amorphous phase boundary material and an experimental verification follows for demonstration and optimization of the impact of surface doping. We conclude that the engineering of the interface using this facile and cost-effective strategy maximizes the crystalline and amorphous phases of metal–metalloids, which can be used to fabricate low-cost and efficient electrocatalysts for water oxidation.

Heteroatom-doping is a practical means to boost RuO₂ for acidic oxygen evolution reaction (OER). However, a major drawback is conventional dopants have static electron redistribution. Here, we report that Re dopants in Re_0.06Ru_0.94O₂ undergo a dynamic electron accepting-donating that adaptively boosts activity and stability, which is different from conventional dopants with static dopant electron redistribution. We show Re dopants during OER, (1) accept electrons at the on-site potential to activate Ru site, and (2) donate electrons back at large overpotential and prevent Ru dissolution. We confirm via in situ characterizations and first-principle computation that the dynamic electron-interaction between Re and Ru facilitates the adsorbate evolution mechanism and lowers adsorption energies for oxygen intermediates to boost activity and stability of Re_0.06Ru_0.94O₂. We demonstrate a high mass activity of 500 A g_cata.⁻¹ (7811 A g_Re-Ru⁻¹) and a high stability number of S-number = 4.0 × 10⁶ n_oxygen n_Ru⁻¹ to outperform most electrocatalysts. We conclude that dynamic dopants can be used to boost activity and stability of active sites and therefore guide the design of adaptive electrocatalysts for clean energy conversions.