Cobalt Phosphide Catalysts Derived From ZIF-67 For Efficient Overall Water Splitting

With the global warming and energy crisis,it is of great urgency and importance to develop safe,green and sustainable energy technologies.Water electrolysis to release hydrogen is one of the most promising ways to deal with the above issues.However,the severe uphill nature of hydrolysis reaction determines that efficient noble metal catalysts should be involved,such as Pt-based catalysts for hydrogen evolution reaction?HER?and Ru O₂and Ir O₂for oxygen evolution reaction?OER?.Considering the high price and the scarcity of these noble metals,the development of highly efficient and stable non-noble-metal-based catalysts has received much research interest in the field.In this regard,a bifunctional electrocatalyst which is highly effective and low-cost for both HER and OER is highly desired.Non-noble metal bifunctional electrocatalysts are ideal catalysts for water electrolysis.However,the construction of a water electrolyzer using a sole catalyst without compromising either its OER or HER performance is still challenging.In this thesis,we develop a simple synthsis strategy,using the Metal-organic frameworks?MOFs?as the precursor to integrate two-dimensional?2D?/zero-dimensional?0D?Co P into the same MOF derived hollow nitrogen-doped carbon nanotube assembly polyhedron.The unique hierarchical structure endowed the resulting nanocomposite with both the advantages of more exposed active sites for 2D and large surface-to-volume ratio for 0D materials;while the hollow interior could benefit charge and mass transfer.Therefore,the as-synthesized Co P/HNCNP@2D Co P could behave as an efficient bifunctional catalyst for water electrolysis,exhibiting decent OER and HER activity with an overpotential of only 220 m V and 173 m V at 10 m A cm^-2,respectively.When the Co P/HNCNP@2D Co P was employed as both the anode and cathode for overall water splitting,a low cell voltage of 1.59 V was required to achieve the current density of 10m A cm^-2.This study reported the intergration of the same metal phosphide phase with diverse dimensions within the same precursor-derived carbonaceous material through a simple preparation strategy,which not only produced an attractive low-cost electrocatalyst for efficient overall water splitting,but also may open up a new avenue to explore the use of metal-organic framworks for electrolytic applications.The insight of integrating the same metal phosphide phase with diverse dimensions might inspire new thoughts to design hierarchical nanostructures towards advanced energy conversion applications.