In Situ Tetraethoxysilane-Templated Porous Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ Perovskite for the Oxygen Evolution Reaction

The perovskite Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) is one of the best catalysts for the oxygen evolution reaction (OER), which is critical to many energy-storage applications. However, the catalytic activity of BSCF perovskites is constrained by a low specific surface area (0.5m²g^-1). We report here, for the first time, a facile, in situ template method using tetraethoxysilane (TEOS) to synthesize porous BSCF with surface areas of up to 32.1m²g^-1, which to our knowledge is the highest reported surface area in a BSCF perovskite, and with excellent catalytic activity for the OER. For example, the BCSF prepared using a TEOS-to-BSCF ratio of 3.4 exhibited up to 35.2Ag^-1 at 1.63V versus a reversible hydrogen electrode (overpotential, η=0.4V) and this current is 5.3 times that exhibited by nonporous BSCF (6.6Ag^-1). The high activity of the porous BCSF is attributed to the additional catalytic surface sites available in the pores created by the in situ TEOS-template method. The general application of this technique to produce porous perovskites is demonstrated in the synthesis of a second example, porous LaMnO₃.