Controllable Synthesis Of Iron - Based Metal Complexes With Interface And Their Electrical Decomposition

Development of low-carbon, high-efficient and diverse energy conversion technology, as one of hot topics, is an effective strategy to solve the issues of energy crisis and environmental pollution. Electrochemical water splitting is a high-efficiency, economical, and eco-friendly technology to generate and store hydrogen fuel using the intermittent renewable sources. The key to minimizing the overpotential is effective electrocatalysts, which can accelerate the electrolysis water reaction. Therefore, it has an important theoretical and practical significance for achieving energy-efficient storage and transformation, to develop the simple and efficient synthetic strategies for transition-metal-based electrocatalysts, explore the relationship between microstructure and macroscopic properties of the catalyst, and understand the catalytic mechanisms.Based on the essence of water electrolysis, including hydrogen evolution reaction(HER) at cathode and oxygen evolution reaction(OER) at anode, in this thesis, a series of composites based on iron- serial bimetal oxides(phosphorus, nitrides) and reduced graphene oxide were designed and synthesized via in situ reduction and interface-directed assembly, which exhibited high catalytic activity towards the OER, HER, and overall water splitting. The main contents of this paper are as follows:(1) CoNiP/rGO composites were designed and synthesized via controlling the synchronous reduction and assembly at two-phase interface, and the successive low-temperature phosphidation. At the interface, GO could paly the the anchoring effect on the generated metal-oxide clusters, which also effectively restrained the agglomeration of CoNiP, yielding particularly small-sized phosphorus. Due the numerous exposed active sites and the synergy effect between Co and Ni metal, the resulting CoNiP/rGO presented high catalytic activity towards HER, slightly superior to CoP/rGO and NiP/rGO.(2) 2D nanosheets with randomly cross-linked CoNi layered double hydroxide(LDH) and small CoO nanocrystals were designed and synthesized via in situ reduction and interfacedirected assembly in air. The formation of CoNiLDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal-oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O2p orbitals, and electron transfer between metal atoms through Ni-O-Co, a number of Co and Ni atoms in the CoNi LDH present a high +3 valency. These unique characteristics result in a high density of oxygen evolution reaction(OER) active sites, improving the affinity between OH- and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER.(3) FeNi3/FeNi3N-N/rGO composites were designed and synthesized via controlling the synchronous reduction and assembly at two-phase interface, and the successive high-temperature nitridation. At the interface, GO could paly the the anchoring effect on the generated metal-oxide clusters, which also effectively restrained the agglomeration of nanoparticles, yielding particularly small-sized bi-metal nitrides. Due the numerous exposed active sites, the synergy effect between FeNi3 alloy and Fe Ni3N, the resulting FeNi3/FeNi3N-N/rGO presented high catalytic activity towards full water splitting.