Solar production of hydrogen using defect engineered boron-rich photocalysts
The inventive concepts disclosed relate to the production of green and blue hydrogen from hydrocarbons using visible light (from a laser, lamp or sun) and defect-engineered boron-rich photocatalysts. We demonstrate that the environment of the B atoms in the lattice can be tuned to favor the dehydrogenation of desired hydrocarbons on reaction sites under visible light. In addition to the hydrogen produced in gas form, carbon atoms are captured by the catalyst and form structures of potential higher value for future applications. Further study of the dark carbonaceous product revealed a graphitic aspect of the material. These findings highlight a new functionality of 2D materials for visible light-assisted capture and conversion of hydrocarbons, with great potential for green hydrogen production—i.e, hydrogen produced from renewable energy and without the release of CO or CO 2 .
1 . A method for of making hydrogen without carbon release in gas form, the method comprising the steps of: (i) forming a reaction mixture by contacting a heterogeneous catalyst comprising at least hexagonal boron nitride with a hydrocarbon source in a chamber, and (ii) focusing a light source on the reaction mixture under conditions that result in formation a carbon structure and hydrogen gas.
2 . The method of claim 1 , wherein the hexagonal boron nitride heterogeneous catalyst further comprises at least one or more catalytically active defect is selected from the group consisting of Stone-Wales defects, B/N defects, boron substituted nitrogen, nitrogen substituted for boron, carbon substituted for nitrogen, carbon substituted for boron, boron vacancy, nitrogen vacancy, and combinations thereof.
3 . The method of any of claim 1 , wherein the heterogeneous catalyst is substantially free of metals, (ii) wherein the hydrocarbon source is selected from a group comprising of methane, ethane, propene, allene, propyne, cyclohexene (iii) wherein the chamber is pressurized up to 276 KPA, (iv) wherein the light source comprises an excitation laser, a UV LED, a high intensity discharge lamp, or a solar source, and/or (v) wherein the chamber has a temperature of 24 to 80° C.
4 . The method of claim 3 , wherein the light source is an excitation laser, wherein the excitation laser has a wavelength from 380 nm to 750 nm, and wherein the excitation laser has a power from 4 mW to 500 mW.
5 . The method of any of claim 1 , wherein the produced carbon structures primarily composes graphitic carbon.
6 . The method of claim 1 , wherein the heterogeneous catalyst further comprises at least partially boron-rich solids consisting of low dimensionality non-equilibrium carbon.
7 . The method of any of claim 1 , wherein the light source comprises an excitation laser, a UV LED, a high intensity discharge lamp, or a solar source.
8 . The method of claim 1 , wherein the hydrocarbon source is selected from a group comprising of methane, ethane, propene, allene, propyne, cyclohexene, and other hydrocarbons.
9 . The method of claim 1 wherein the heterogeneous catalyst further comprises at least partially boron-rich solids consisting of low dimensionality non-equilibrium carbon.
10 . The method of claim 1 , wherein the hexagonal boron nitride has at least one catalytically active defect on a surface thereof.
11 . The method of claim 1 , wherein the solar irradiation is focused by a focusing element such as a conventional lens, a Fresnel lens, parabolic mirrors, a mirror array, or a lens array.
12 . The method of claim 1 , wherein the solar irradiation is focused to a spot with an area of 1 cm 2 to 4 cm 2 .
13 . The method of claim 1 , wherein the solar irradiation is focused to a spot to produce an irradiance of 5 to 20 W/cm 2 .