Si dopeded Fe-MOF as efficient bifunctional catalyst for overall water splitting

Electrocatalytic water decomposition couple with renewable energy is considered as a green and sustainable method for hydrogen production. However, the development of non-precious metal bifunctional catalysts remains one of the major bottlenecks in electrochemical water decomposition, hindering the key challenges for its commercial application. In this paper, we report a simple and rapid synthesis of an iron metal-organic skeleton (Fe-MOF) precursor at room temperature via the flash nanoprecipitation (FNP) technique. The precursor reacts with SiCl4 to derive a Si-Fe-MOF catalyst with mesoporous structure. The electrochemical performance tests reveal that compared to Fe-MOF, Si-Fe-MOF exhibits significantly better performance, with overpotentials of 181 mV and 269 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) respectively (while Fe-MOF has overpotentials of 297 mV for HER and 337 mV for OER) at a current density of 10 mA cm(-2), and it possesses superior stability, respectively, at 10 mA cm(-2), and has superior stability. Meanwhile, Si-Fe-MOF is used as a bifunctional catalyst with a full hydrolysis voltage of 1.62 V. It is found by in situ Raman spectroscopic characterization that Si-Fe-MOF is converted from Fe metal sites to more active FeOOH during the OER process. DFT calculations show that the doping of Si atoms in Si-Fe-MOF optimize the electronic structure of the catalyst and optimize the reactive intermediates' adsorption.