مشخصات پژوهش

In recent years, there has been a growing interest in developing organic materials for hydrogen evaluation due to their low cost, aqueous and photo stability, and tunable bandgaps. Graphitic carbon nitrides are the most important class of organic semiconductors for this application [1]. Recently, however, new classes of materials are being investigated for hydrogen evolution from water, such as nitrogen doped graphene oxide [2], covalent organic frameworks [3], conjugated porous and linear polymers [4,5]. The most organic semiconductors have required an additional metal co-catalyst to produce an appreciable hydrogen evolution reaction, often introduced by Pt nanoparticles [6], or the addition of a molecular catalyst [7,8]. However, recent reports of photocatalysis employing both linear and cross-linked conjugated polymers suggest that these systems are able to produce hydrogen without any added co-catalyst [9]. Activity of linear and cross-linked conjugated polymers without the need for co-catalysts with precious metals or unstable molecular complexes [10], could be a very attractive property for reduction of the cost and complexity of current photocatalytic systems. A feature of these polymers that has not yet been systematically studied is the presence of significant quantities of residual Pd originating from their synthesis via Pd catalyzed polymerization reactions. Therefore, it is possible that the residual Pd facilitates HR2R evolution and removes the need for additional co-catalysts. A fundamental key to understanding how catalytic and photocatalytic reactions work requires knowledge of energy profile of reaction pathways. Nowadays there has been access to many experimental structures of catalysts that make it easy to design more potent catalyst compounds. Besides using experimental data, computational methods based on DFT play an important role in modern catalysis development process. Furthermore, DFT calculations are conducted to unveil the reaction mechani