Constructing heterophase structures of α-Cu2V2O7/β-Cu2V2O7 to enhance photovoltaic and photocatalytic properties

α-Cu2V2O7 is a rare type of negative thermal expansion materials with weak photoelectric property. It is meaningful to enhance its photoelectric property while tailoring thermal expansion for stable photoelectric conversion efficiency and photocatalytic property. Here, heterophase structures of α-Cu2V2O7/β-Cu2V2O7 are constructed by introducing Li+ into α-Cu2V2O7. With increasing Li content, some of α-Cu2V2O7 transform to β-Cu2V2O7 forming heterophase structures of α-Cu2V2O7/β-Cu2V2O7. The photovoltaic and photocatalytic properties are enhanced owing to the energy level matching between α-Cu2V2O7 and β-Cu2V2O7. The surface photovoltage of Cu1.95Li0.05V2O7 increases the most relative to the pristine sample: 3.7 (400 nm) and 1.4 (475 nm) times. The maximum reduction factor of the absolute value of thermal expansion coefficient of Cu1.91Li0.09V2O7 decreases 2.8 times compared with the pristine sample. The phase transition from α to β-Cu2V2O7 could relate to the introduction of heterovalent ion of Li+ supplying less electron for oxygen.