Template Curvature-Induced Tensile Strain Optimizes the Oxygen Evolution Reaction Activity of α-Co(OH)2

Abstract The high energy barriers of the oxygen evolution reaction (OER) are the main bottleneck in electrocatalytic water splitting, and developing efficient nonprecious metal catalysts is crucial. Here, we report a novel and controllable curvature-induced strain engineering strategy by in situ growing α-Co(OH)2 (showing potential as an OER catalyst) on SiO2 nanospheres with different sizes to form a core–shell structure (denoted as PSCo-X). The curvature-induced tensile strain in the α-Co(OH)2 shell was achieved through the curvature of SiO2 nanospheres, and the strain magnitude was precisely tuned by adjusting the size of the nanosphere core. Characterization results confirm that the generated tensile strain modulates the electronic structure of α-Co(OH)2, thereby enhancing the electron-accepting capability of the cobalt centers. Although the introduction of SiO2 decreases the overall active site density, decreasing the template size and increasing the curvature promote the exposure of active sites. Electrochemical measurements show that PSCo-200 exhibits the optimal OER activity with an overpotential of only 325 mV at 10 mA cm–2, which is superior to that of pristine α-Co(OH)2 (360 mV). Furthermore, the Cdl-normalized intrinsic catalytic activity follows the trend of PSCo-200 > PSCo-300 > PSCo-400 > PSCo-100 > pristine α-Co(OH)2. Additionally, the smaller Tafel slope and lower charge transfer resistance of PSCo-200 facilitate faster reaction kinetics. This work provides an efficient and controllable strategy to enhance the intrinsic activity of α-Co(OH)2 via curvature-induced strain, offering new insights into the rational design of high-performance OER electrocatalysts.