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Herein, a simple control-synthesis of pure α-Bi2O3or Bi2O2CO3was realized for opto-electronics and photocatalytic studies. Precipitation via different precipitants (NaOH, KOH and NH4OH) as well as sol gel techniques have been used to form pure α-Bi2O3or Bi2O2CO3using Bi(NO3)3·5H2O. The XRD analysis verified that pure α-Bi2O3phase was formed through using NaOH and sol–gel techniques while KOH and NH4OH produced pure Bi2O2CO3. The morphological shape of α-Bi2O3(NaOH) powder shows rods structure having different length and diameter. The SEM image of Bi2O2CO3(KOH) powder illustrates cotton-shaped like structure while Bi2O2CO3(NH4OH) powder shows spongy grains shape. The SEM micrograph of α-Bi2O3powder (sol–gel) displays a highly porous network. The optical band gap energy of the α-Bi2O3(NaOH) and α-Bi2O3(sol gel) was found to be 2.88 and 2.91 eV, respectively. On the other hand, Bi2O2CO3-KOH and Bi2O2CO3-NH4OH powders revealed UV band gap energies of 3.56 and 352 eV, respectively. Optically, α-Bi2O3sample revealed a high refractive index value above 2.3. The solar energy photocatalytic tests indicated that α-Bi2O3(sol gel) catalyst has a remarkable efficiency of 78% and 80% to degrade methylene blue (MB) and Congo red (CR) dyes during 210 min, respectively. Bi2O2CO3(KOH) powder exhibits the second highest photocatalytic activity for MB and CR dyes reached to 71% and 77% under sunlight irradiation. The high performance of α-Bi2O3(sol–gel) catalyst can be ascribed to the morphological structure, high crystallinity, wide light absorption and well charge separation.