Constructing LaNiO3/NiO heterostructure via selective dissolution of A-site cations from La1−xSrxNiO3 for promoting oxygen evolution reaction

The construction of perovskite/metal oxide heterostructure is a practical approach to enhancing the catalytic activity of perovskite oxides for oxygen evolution reaction (OER). The heterostructures are generally fabricated by physical/chemical deposition with inferior controllability. This work presents a facile acid etching method to construct a LaNiO3/NiO heterostructure from La1–xSrxNiO3 perovskite oxides. The selective dissolution of A-site elements in acid facilitates the exsolution of Ni to form NiO nanoflakes on the surface. The phase evolution of La1–xSrxNiO3 upon acid etching is associated with both Sr content and etching duration. For La0.95Sr0.05NiO3 etched for 10 h (LSN5–10 h), the obtained catalyst had an overpotential of 385 mV at 10 mA cm–2 in 1 M KOH, 285 mV lower than the pristine LSN5. The turnover frequency (TOF) value obtained at an overpotential of 450 mV is 0.97 S–1, 2.55 times larger than the pristine LSN5, demonstrating its excellent catalytic efficiency. Long-term tests in 1 M KOH further enhanced the OER performance, which could be ascribed to the formation of highly active NiOOH. The excellent OER performance of the LaNiO3/NiO heterostructure is attributed to the efficient charge transfer at the interface and the large surface areas of NiO nanoflakes. This work demonstrates an artificial surface decoration method via surface etching to improve the OER activity and stability of Ni-based perovskite oxides.