Stearic acid-TiO2 composite Janus sheets perpendicular to the interface for emulsification and photocatalysis

•Novel 2D TiO2 Janus sheets (V-STA-TiO2 JNs) with different structures and properties at each side of the same plane were designed and prepared via a simply and easily operated impregnation method.•V-STA-TiO2 JNs can be used as emulsifier to prepare Pickering emulsion and existed vertically at the oil–water interface.•V-STA-TiO2 JNs have better emulsifying effect and more effective catalytic effect than the traditional Janus sheet emulsifiers, and their self-degradation can be ignored.