| The global energy market relies mainly on fossil fuel supplies and world energy demand will roughly triple by the end of the century. Because of the non-renewable nature and polluting combustion products of fossil fuel, it is vital to find and develop clean renewable energy substituting for fossil fuel. Hydrogen is a potential and attractive alternative to conventional fuels due to its highly natural abundance, non-toxicity, high heating value per unit mass as well as ecb-friendliness. Utilization of intermittent solar and wind energy, as energy sources existing freely in nature, is swayed by alternating day and night and climatic variation, which introduces load security risks into energy grids. Therefore, converting them to hydrogen efficiently via appropriate way is of the utmost importance. Water electrolysis and photoelectrolysis are endowed with the possibility to produce ultra-pure hydrogen in an environmental-friendly way, because its feedstock is water-an abundant, accessible source and the combustion product of hydrogen is water-the only reactant for the process, which means recycling water and contains the most sustainable steps. We focused on exploiting and developing the new and facile synthesis strategy to prepare the anode materials for water electrolysis and photoelectrolysis that are characterized by advanced technology in detail. We have designed and achieved the following work:(1) The anodic reaction of water electrolysis, namely, the oxygen evolution reaction (OER), is kinetically sluggish and efficiency-limiting because of a four-electron redox process (4OH-?O2+2H2O+4e-) resulting in high overpotential concerned with O-H bond breaking and O-O bond formation that severely impede its widespread application. Some precious metal oxides, such as IrO2 and RuO2, exhibit excellent OER activity. However, their high cost, scarcity, and rapid deactivation hinder their use. Inspired by the above consideration, we highlight the abundant transition metal compounds as the research object for obtaining 2D Co-based hydroxide ultrathin nanosheets (HUNSs) based on the simple liquid decomposition of Co-based acetate hydroxide metal-organic frameworks (AHMOFs) into hydroxide layered nanosheets (HLNSs) after adding alkaline solution to the AHMOF precursors for replacing acetate ligands with hydroxyl ions and exfoliation of the obtained HLNSs by water molecules and freed acetate ligands through fully ultra-sonication at room temperature without involving additional reagents for exfoliating. We successfully achieved Co, CoZn and CoNi HUNSs benefiting from the high component controllability of the Co-based AHMOFs and CoNi HUNSs showed the optimal catalytic activity for the OER outperforming the IrO2 nanoparticles along with the high stability.(2) We introduced visible light into a new research system for the purpose of converting it to electricity and then to hydrogen. We have constituted a 3D nano-heterojunction (NHJ) architecture-CdS nanolayer conformed with nanoporous gold (NPG/CdS) through simple and in situ galvanostatic electrodeposition. This intriguing platform integrating the macro-and nano-properties of gold not only provides open carrier transfer pathways with high electric conductivity but significantly promotes strong plasmon-exciton coupling conducive to boosting charge-separation and suppressing excition-recombination. Consequently, NPG/CdS NHJ showed broad and strong visible light absorption bands and excellent photocurrent under visible light representing high photoelectrochemical hydrogen evolution activities. Moreover, NPG/CdS NHJ possessed stable catalytic activity within 104 s irradiation due to NPG as the scavenger to capture the photo-excited holes with strong oxidability in the valence band of CdS. |
PDF Full Text Request