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Description
The Project and its outcomes’ target is an important contribution to solving a worldwide environmental issue. Efficient electrolysis of water is commonly seen as a way to accumulate the excess energy that may be produced by some renewable sources, as photovoltaics. This excess could power the electrolysis process, which yields hydrogen, i.e., the fuel with the highest energy density per volume unit. This concept is in line with hydrogen economy perspectives. The crucial element for water electrolysis is an efficient electrode design which enables a low split potential alongside high durability. Another key matter is the elimination of platinum from electrode manufacturing. The Project’s aim is the synthesis of such electrode materials and practical verification of their application-oriented features. The main objectives are to obtain catalysts, i.e., 3D-structured graphene enriched with heteroatoms, metal oxides, and perovskite metal oxides. The key innovation is the synthesis of new electrode noble-metal-free materials itself. The catalysts most promising from the perspective of water splitting will be discerned and described in detail on the basis of physical and chemical analyses. The synthesis strategy will be established taking into account the high variability of metal oxides, heteroatom dopants, and perovskite metal oxides. The chemical state of atoms will be examined and characterized to make it possible to choose the most effective catalysts for the oxygen evolution reaction and hydrogen evolution reaction. This way, we will gain a precise determination of catalyst site types, which will be particularly important for the interpretation of electrochemical measurements. Important step is determine the relationship of morphology and elemental composition with the materials’ electrochemical and photoelectrochemical (water splitting) activity, as well as their hydrogen evolution reaction activity in contact with aqueous electrolytes.
Summary of project results
The Project and its outcomes’ target is an important contribution to solving a worldwide environmental issue. Efficient electrolysis of water is commonly seen as a way to accumulate the excess energy that may be produced by some renewable sources, as photovoltaics. This excess could power the electrolysis process, which yields hydrogen, i.e., the fuel with the highest energy density per volume unit. This concept is in line with hydrogen economy perspectives. The crucial element for water electrolysis is an efficient electrode design which enables a low split potential alongside high durability. Another key matter is the elimination of platinum from electrode manufacturing. The Project’s aim is the synthesis of such electrode materials and practical verification of their application-oriented features. The main objectives are to obtain catalysts, i.e., 3D-structured graphene enriched with heteroatoms, metal oxides, and perovskite metal oxides. The key innovation is the synthesis of new electrode noble-metal-free materials itself. The catalysts most promising from the perspective of water splitting will be discerned and described in detail on the basis of physical and chemical analyses. The synthesis strategy will be established taking into account the high variability of metal oxides, heteroatom dopants, and perovskite metal oxides. The chemical state of atoms will be examined and characterized to make it possible to choose the most effective catalysts for the oxygen evolution reaction and hydrogen evolution reaction. This way, we will gain a precise determination of catalyst site types, which will be particularly important for the interpretation of electrochemical measurements. Important step is determine the relationship of morphology and elemental composition with the materials’ electrochemical and photoelectrochemical (water splitting) activity, as well as their hydrogen evolution reaction activity in contact with aqueous electrolytes.
The core synthesis strategy (WP1) was established taking into account the high variability of metal oxide (Co3O4, CeO2, Fe2O3, TiO2, La2O3, MoO2), perovskite-type metal oxide (MnCo2O4, CoMoO4, SrMoO4, La0.8Sr0.2MnO3, Bi2WO6, perovskite-type oxide containing praseodymium, barium, strontium, cobalt, and iron atoms) and heteroatom-doping (nitrogen, boron, phosphorus, and dual doping with nitrogen and phosphorus or nitrogen and boron). 3D-structured graphene flakes served as a basic carbon matrix for heteroatom insertion, for which different approaches were employed. Commercial graphene is chosen for economic reasons, i.e., the cost of manufacturing must be acceptable in any further massive application. Furthermore, 3D-graphene matrix almost automatically provides two key features, i.e., chemical stability and high electric conductivity. While preparing samples, we considered the need to control the structure and elemental composition of those produced in laboratory experiments, and we compared the results between different series. The porosity and chemical state of surface atoms were examined and characterized to make it possible to choose the most effective catalysts for the oxygen evolution reaction and hydrogen evolution reaction.
General analysis of electrochemical performance (WP2) was made and impedance spectroscopy was measured in alkaline, neutral, or acidic media. The slow kinetics of both the hydrogen evolution reaction and the oxygen evolution reaction require high overpotentials to achieve significant current density. Hybrid electrocatalysts have been used to increase efficiency and reduce energy consumption in the electrochemical process. The results of OER and HER analyses were integrated with the elemental composition and porosity parameters of samples. For the HER and OER responses, the achieved overpotentials were determined at current densities of -10 mA/cm2 and 10 mA/cm2, respectively. From analyzed many series of samples, e.g., the obtained spinel MnCo2O4 structures on exfoliated graphite - new hybrid structures are bifunctional catalysts, exhibiting excellent electrocatalytic performance and very good working stability for both the HER and OER. It was confirmed that the new noble-metal-free electrode materials and with metal oxides or perovskite-type metal oxides could compete with ones containing noble metals.
The last WP3 was a direct consequence of the WP1 and WP2 tasks’ results, where we selected electrodes with high electrochemical performance in HER and/or OER reaction. The information gathered on the catalytic efficiency of the obtained materials made it possible to select of 6 materials (TiO2/SrMoO4/CoMoO4/GO; MnCo2O4/EG (2/1); PrOX:C (1:2); PrOX:C (1:2); NiCo2O4/C1; BiMoVOx/GF) with the highest activity and was evaluated their usefulness in producing green hydrogen and we estimated of their production costs.
The Project entitled “Pt-free graphene-based catalysts for water splitting technology as green method for hydrogen production” and its outcomes’ target is an important contribution to solving a worldwide environmental issue. Efficient electrolysis of water is commonly seen as a way to accumulate the excess energy that may be produced by some renewable sources, as photovoltaics. This excess could power the electrolysis process, which yields hydrogen, i.e., the fuel with the highest energy density per volume unit. This concept is in line with hydrogen economy perspectives. The crucial element for water electrolysis is an efficient electrode design which enables a low split potential alongside high durability. Another key matter is the elimination of platinum from electrode manufacturing. The Project’s aim was the synthesis of such electrode materials and practical verification of their application-oriented features. The main objectives were to obtain catalysts, i.e., graphene enriched with heteroatoms, metal oxides, and perovskite metal oxides. The key innovation is the synthesis of new electrode noble-metal-free materials itself. The catalysts most promising from the perspective of water splitting were discerned and described in detail on the basis of physical and chemical analyses. The synthesis strategy was established taking into account the high variability of metal oxides, heteroatom dopants, and perovskite metal oxides. The chemical state of atoms was examined and characterized to make it possible to choose the most effective catalysts for the oxygen evolution reaction and hydrogen evolution reaction. This way, we gained a precise determination of catalyst site types, which was particularly important for the interpretation of electrochemical measurements. Important step is determine the relationship of morphology and elemental composition with the materials’ electrochemical and photoelectrochemical (water splitting) activity, as well as their hydrogen evolution reaction activity in contact with aqueous electrolytes. The information gathered on the catalytic efficiency of the obtained materials made it possible to select of materials with the highest activity and was evaluated their usefulness in producing green hydrogen and we estimated of their production costs which is lower than for commercial catalysts based on noble metals.