In the present study, Li2B4O7/LiBO2/Li3BO3 (LBO) nanocomposites were synthesized by a modified Pechini sol-gel route utilizing the mixture of different polybasic acids and gelling agents. This work demonstrated that by controlling the reaction variables including kind of polybasic acids and gelling agents, pH and mole ratio of polybasic acid to total metals, the LBO nanostructures with various morphologies and particle sizes were prepared. Furthermore, the LBO nanocomposites showed excellent TOC removal (70%) and photocatalytic efficiency (91%) in order to photodegradation of acid violet 7 azo dye as water pollutant under UV light irradiation. Moreover, compared to commercial P25 photocatalyst, the LBO heterostructures exhibited higher photodegradation activity for removal of acid violet 7 dye in 90 min under UV light irradiation, even after four times cycles. The excellent photocatalytic degradation of LBO photocatalyst can be ascribed to the strong photon absorption, high-efficiency charge carrier separation, uniform particle size and appropriate band gap energy of the nanocomposite. Also, radical trapping capability test exhibited that the photoinduced superoxide radicals (•O2 −) and holes (h+) were the prevailing active species in the photocatalytic performance.