CTPAB can facilitate both HER and OER processes on different surface active sites and the donor-acceptor characteristics is beneficial to effective electron/hole separation and will contribute to high quantum efficiency. However, co-catalysts or external electric potential are necessary to overcome the small energy barrier of HER under light-irradiation. Therefore, 2D CTPAB is predicted to be a promising non-metal photocatalyst or photoelectrocatalyst to facilitate overall water splitting. To summarize, by means of first principles calculations, we have systematically studied the structural, electronic and optical properties of three 2D binary polymers that are made of B-and N-centered HTs and explored their photocatalytic activity for water splitting. The integration of B-and N-centered HTs into a monolayer contributes to the formation of donor-acceptor type 2D networks, which are semiconductors with a direct band gap of 1.98-2.28 eV. The more narrowed band gap and higher dispersion of valence and conduction bands of these 2D binary HT-polymers than that of their unary counterparts, contribute to higher charge carrier mobility and more pronounced light absorption in the visible range of spectrum. With appropriate band edges and sufficient drive potential for both HER and OER, 2D