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Title: Transition metal doped ZIF-67/ZIF-8 catalysts for hydrogen evolution reaction
Author: Qin, Yudao
ISNI:       0000 0004 9359 2155
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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Electrochemical water splitting is a sustainable method of producing hydrogen - the ultimate clean energy carrier. However, high cost and poor stability of the Pt catalyst for hydrogen evolution reaction (HER) hinder its wide applications. Here, the main aim of this project is to develop cost-effective and durable HER catalysts, with a focus on carbonized transition metal (Pt, Co, Ni, Fe, Mo) doped zeolite imidazolate framework (ZIF). (1) The first approach is to obtain high catalyst dispersion while reducing overall catalyst content. More specifically, an ultra-low PtCo bimetallic catalyst embedded in porous carbon was prepared via direct annealing of Pt-doped ZIF-67. The resulting catalyst (CPt@ZIF-67) with only 5 wt.% Pt loading, exhibited superior performance with a Tafel slope of 27.1 mV dec-1 and an overpotential of only 50 mV at current density of 10 mA cm-2. A 24-hour stability test for CPt@ZIF-67 showed negligible activity decay. (2) Non-noble transition metals such as Ni, Fe and Co have been proved to be promising candidates in alkaline electrolytes, but they are easily corroded in acids. Herein, Ni-doped carbon nanowires (CNi@ZIF-8) was simply synthesized via carbonization of Ni-doped ZIF-8. Ni doping could both prevent the aggregation during high-temperature pyrolysis and enhance the exposure of surface active sites. CNi@ZIF-8 demonstrated a Tafel slope of 40.4 mV dec-1 with an overpotential of 141 mV at current density of 10 mA cm-2. The optimized catalyst also gave long-term durability in 0.5 M H2SO4.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available