An Ideal Surface Reveals How Active It Is and Why It Degrades: SrTi 0.5 Fe 0.5 O 3−δ Model Thin Film with Atomically Flat Terraces─A Case Study - Hyunseung Kim; Jiapeng Liu; Kyuseon Jang; Bonjae Koo; Jun Kyu Kim; Jongsu Seo; Chanwon Jung; Pyuck-Pa Choi; Francesco Ciucci; WooChul Jung (Journal of the American Chemical Society, 2026)