Construction Of Heavy Oil-Based Porous Carbon Supported Transition Metal Phosphides And Their Total Water Splitting Performance

Wind,solar,hydrogen,tidal and other clean energy sources are gradually replacing traditional fossil fuels.Among all kinds of clean energy,hydrogen energy is considered as the main energy source for future social development due to its advantages of high calorific value of combustion and wide range of raw materials.Hydrogen production from water electrolysis is an important source of hydrogen energy,because it requires expensive precious metals such as Pt to reduce the reaction overpotential,thus limiting the large-scale application of hydrogen energy.Therefore,the development of efficient,stable and low-cost catalyst for electrolysis of aquatic hydrogen has naturally become the forefront of current world research.In this paper,we used a simple one-pot pyrolysis method,using heavy oil slurry as a carbon source,the composite material combining heavy oil-based transition metal phosphide and single atom doped carbon material was successfully prepared.Namely,cobalt phosphide/Cobalt mono-atom doped porous carbon material（Co₂P/Co-N-C）and cobalt phosphide/nickel-cobalt/Nickel-cobalt double mono-atom doped porous carbon material（Co P/Ni Co P/Ni-Co-N-C）,and characterized by a series of means,the specific research content is as follows:（1）First,we prepared cobalt phosphide/cobalt single-atom-doped porous carbon by a simple coordination reaction and subsequent one-pot pyrolysis using graphitized carbon nitride as a template and catalytically cracked oil slurry as a carbon source.Material（Co₂P/Co-N-C*）.Co is doped in the carbon layer in the form of single atoms,while Co₂P exhibits a dual structure of nanoparticles and nanorods under the catalysis of heavy oil.Compared with Co₂P/Co-N-C,composites exhibited excellent electrolytic water reaction catalytic activity.Under the action of heavy oil,Co single atom and Co₂P show a more excellent synergistic effect.Co₂P/Co-N-C*composites can reach the current density of 10,100 and 200 m A·cm^-2 in HER reaction only needed 61,189 and 270 m V,respectively.Similarly,in OER reaction,the current density of 10 m A·cm^-2 is only 248m V.At the same time,the composite can maintain a stable working state for a long time,with almost no decay after 2000 cycles of CV.（2）Based on the optimization of Co₂P/Co-N-C*composites,we added Ni species in the system,The Co P/Ni Co P/Ni-Co-N-C was successfully prepared.Therefore,the introduction of Ni species greatly stabilized the Co mono-atom,resulting in more defects on the carbon layer and exposing more active sites.At the same time,the Co P/Ni Co P compounds formed form heterogeneous structures,through the synergistic effect,the electrolysis water catalytic activity of the composite material was further improved.In HER reaction,only 40,178 and 245 m V were needed to reach the current density of 10,100 and 200 m A·cm^-2 respectively,and keep the excellent catalytic activity for stable work.In this paper,a high activity water electrolysis catalyst with heavy oil-based transition metal phosphating compound and monatomic carbon material has been successfully designed,which provides a new design method and idea for the large-scale preparation of water electrolysis catalyst.