Strain regulation has become an important strategy to tune the surface chemistry and optimize the catalytic performance of nanocatalysts. Herein, the construction of atomic‐layer IrOx on IrCo nanodendrites with tunable IrO bond length by compressive strain effect for oxygen evolution reaction (OER) in acidic environment is demonstrated. Evidenced from in situ extended X‐ray absorption fine structure, it is shown that the compressive strain of the IrOx layer on the IrCo nanodendrites decreases gradually from 2.51% to the unstrained state with atomic layer growth (from ≈2 to ≈9 atomic layers of IrOx), resulting in the variation of the IrO bond length from shortened 1.94 Å to normal 1.99 Å. The ≈3 atomic‐layer IrOx on IrCo nanodendrites with an IrO bond length of 1.96 Å (1.51% strain) exhibits the optimal OER activity compared to the higher‐strained (2.51%, ≈2 atomic‐layer IrOx) and unstrained (>6 atomic‐layer IrOx) counterparts, with an overpotential of only 247 mV to achieve a current density of 10 mA cm−2. Density functional theory calculations reveal that the precisely tuned compressive strain effect balances the adsorbate–substrate interaction and facilitates the rate‐determining step to form HOO*, thus assuring the best performance of the three atomic‐layer IrOx for OER.

Polymer monoliths with open pores and median pore size of about 15 nm-3 lm have been successfully synthesized by photoinitiated polymerization of butyl methacrylate and ethylene glycol dimethacrylate monomers. The solubility of the monomers in a porogenic solvent is determined by Hildebrand solubility parameter, and it is found that it has great effect on the pore size of the polymers synthesized. Polymers with larger pores are usually generated with poorer solvents for the monomers. However, polymers with different pore sizes and porosities have been obtained using porogenic solvents with similar Hildebrand solubility parameters. The evaporation rate of the porogenic solvents might be another critical factor affecting the properties of the polymer monoliths. Moreover, the effect of water as a cosolvent on the pore size and porosity of the polymers have also been investigated. Polymers with larger pore size have been prepared with the presence of water due to the occurrence of earlier phase separation in the polymerization.

Porous monoliths have been successfully prepared by photoinitiated polymerization of hydroxyethyl methacrylate and ethylene glycol dimethacrylate monomers in a porogenic solvent. By varying the composition of the starting solutions such as initiator fraction, monomer ratio and pore generator (porogen) fraction and type, as well as UV intensity, monoliths have been obtained with narrow pore size distribution and median pore size from about a few nanometres to a few micrometres. © 2012 Society of Chemical Industry

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