Solar-Driven Electrochemical Green Fuel Production from CO₂ and Water Using Ti₃C₂T_x MXene-Supported CuZn and NiCo Catalysts

The scope of our work broadly addresses the synthesis, characterization and analysis of novel disruptive binder, free catalyst films to produce solar fuels from water and carbon dioxide. The main challenge in the field include low paraic efficiencies in adequate production rates, long-term catalyst, durability, and the scalability of the system. To begin, clean the nickel foam using acetone, then sonicate the nickel foam in deionized water for five minutes.

Under the fume hood, soak the carbon fiber paper in one molar nitric acid for 20 minutes to activate it while wearing gloves and appropriate personal protective equipment. Immerse the cleaned nickel foam and MXene solution for five minutes. After drying the sample, label it as MXene nickel foam.

Now load 50 milliliters of MXene solution into a spray gun and spray the solution onto the nickel foam. Next, add copper and zinc precursor solutions into a glass electrochemical cell. Insert a silver or silver chloride reference electrode, a platinum counter electrode and the MXene carbon fiber paper working electrode into the cell.

Then connect each electrode to its respective terminal on the potential stat. Apply the given pulsed current deposition sequence and repeat for 1, 000 times to deposit the copper zinc layer. In a separate electrochemical cell, add nickel and cobalt precursor solutions.

Use the same electrode configuration, but replace the working electrode with the MXene nickel foam. Prepare the electrolyte bath with 50 milliliters of 50 millimolar nickel nitrate in cobalt nitrate, dissolved in deionized water. Connect all electrodes to the appropriate inputs on the potential stat, ensuring the MXene nickel foam is connected as the working electrode.

Apply the same pulse deposition cycle as previously demonstrated for 1, 000 sets to obtain nickel cobalt integrated titanium carbide MXene nickel foam. To assemble a two compartment hydrogen cell, insert an alkaline exchange membrane to separate the two chambers. Use nickel foam as the anode and a two centimeter by two centimeter copper at titanium carbide MXene on carbon fiber electrode as the cathode.

Then fill both chambers with one molar potassium hydroxide solution as the electrolyte. Check the membrane junction thoroughly for any electrolyte leaks and tighten the junction if needed. Now insert a mercury or mercury oxide reference electrode into the cathode chamber and seal the entire system to ensure it is gas tight.

Add one tube for carbon dioxide inlet and another for the gas outlet in the cathartic chamber. Then purge carbon dioxide into the cathartic chamber at a rate of 30 milliliters per minute for 15 minutes to saturate the electrolyte. Illuminate the photovoltaic cell with one sun intensity and connect it to the cell.

Now record cyclic voltammetry from zero volts to 2.5 volts at a scan rate of 50 millivolts per second and EIS at open circuit potential. Perform a zero amp chronoamperometric measurement for two hours. Record the current periodically using a multimeter to calculate the Faradic efficiency of the products.

Connect the gas outlet of the cathodic chamber to a gas chromatograph for inline sampling every 10 minutes. Program the gas chromatograph to detect and quantify permanent gases using a packed column such as a molecular sieve. Set the oven temperature to start at 150 degrees Celsius with a two minute hold.

Then ramp to 200 degrees Celsius with a one minute hold for effective separation and evolution of gases. Repeat the H cell assembly using nickel cobalt at titanium carbide MXene nickel foam as the anode and platinum on carbon coated nickel mesh as the cathode. Insert a mercury or mercury oxide reference electrode into the anechoic chamber along with the working electrode.

Fill both chambers of the H cell with one molar potassium hydroxide solution. Record cyclic voltammetry from zero volts to 1.2 volts at a scan rate of 50 millivolts per second and EIS under open circuit conditions. Use the OCP determination function on the auto lab potential stat to record the open circuit potential.

Now illuminate the photovoltaic cell using a solar simulator positioned five centimeters away set to one sunlight intensity. Connect the terminals of the photovoltaic cell to the electrodes and perform a 0 amp chronoampetontiometric measurement. Monitor and log the current continuously for efficiency calculations.

Now connect the gas outlet of the cathode chamber to a gas chromatograph. Then analyze hydrogen gas production every 10 minutes using a thermal conductivity detector and nitrogen as the carrier gas. After washing the components with water, start assembling a zero gap electrolyzer cell.

Prepare clean polyvinyl propylene tubing and attach compatible push and pull valves to create junctions between different parts of the alkaline water electrolysis setup. Stack the cell components sequentially starting with the cell anode plate nickel cobalt at titanium carbide MXene and Ni-foam anode, gasket, alkaline exchange membrane, another gasket, platinum carbon cathode, and finally, the cathode cell plate. Use alignment rods if available or firmly position the layers manually on a table to keep them in place.

To assemble the zero gap electrolyzer, align all layers and end plates properly and secure them using screws. Connect the assembled cell to peristaltic pumps circulating 30%potassium hydroxide at a flow rate of 30 milliliters per minute. Maintain the electrolyte reservoir at 60 degrees Celsius using an oil bath.

Monitor the temperature with a probe and avoid touching the cell or reservoir without thermal gloves. The diffraction pattern of titanium aluminum carbide MXene exhibited characteristic peaks for metal aluminum carbide structure. After selective etching and delamination, the peaks shifted to lower angles suggesting the synthesis of titanium carbide MXene.

The scanning electron microscope image of the titanium aluminum carbide MXene phase revealed its layered morphology. After selective etching and delamination, the scanning electron microscope image of titanium carbide MXene deposited on an Illumina anodic template exhibited a flake like morphology consisting of single to few layers. X-ray diffraction and scanning electron microscope images confirmed the structures of copper zinc at titanium carbide MXene at carbon fiber paper and nickel cobalt at titanium carbide MXene at nickel foam.

Cyclic voltammetry measurements in one molar potassium hydroxide showed distinct curves for carbon dioxide reduction by copper zinc at MXene and carbon fiber paper and for water electrolysis by nickel cobalt at MXene and nickel foam. EIS revealed different resistance profiles for the cathode copper zinc at MXene and CFP in carbon dioxide reduction and the anode nickel cobalt at MXene and nickel foam in water electrolysis. The CV profile and chrono amperograms were observed at different applied cell potentials.

A biometallic system, lower over potential, perform well at industrial current density and has long operation hours. We're addressing the synthesis of novel, economical, and scalable and abundant for a functional biomechanic anode and cathode for carbon dioxide reduction in water solubility. Our findings paved the way to new one step film deposition that can lead to multicarbon products and green hydrogen generation at low power consumption.