The electronic properties and optical properties of doped beta-Bi2O3 have been studied using spin-polarized density function theory (DFT) with the aim of realizing the photocatalytic hydrogen generation under visible light irradiation. The results show that IIIA elements (Al, Ga, In and Tl) mono-doping increase the necessary redox potentials in energy for water splitting, but the increasing of band gap decreases the visible light absorption. Moreover, co-doping in beta-Bi2O3 can overcome this problem by increasing the light absorption and simultaneously realizing water splitting by sunlight. The N/Al and N/Ga co-doped beta-Bi2O3 introduce the delocalized band, which extend the light absorption but has limited benefit for photocatalytic activity. Importantly, N/In and N/Tl co-doping shift the mid-gap states toward the valence band edge to create an extend valence density of states, which can improve the light absorption. In particular, N/In co-doping leads to the narrowed band gap and a stronger potential for photocatalytic activity toward hydrogen evolution from water, which may play an important role in the development of bismuth oxides for more effective utilization of the solar spectrum for fuel production. (C) 2014 Elsevier B.V. All rights reserved.