Abstract:

Electrochemical water splitting is a very sustainable and promising process for hydrogen fuel production in which two half-reactions are involved: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Although water splitting is a well-established technology, still, there are several limitations for the large-scale production of hydrogen using this process. Firstly, the most important factor is the OER process that requires more electrical energy. Secondly, the unavoidable mixture of oxygen gas with hydrogen gas may propel the reaction to an explosion in the electrolyzer. Additionally, O₂ existence can contribute to reactive oxygen species (ROS) formation which damages the membrane and the surface of electrodes. Several approaches have been suggested to reduce energy consumption, avoid the possibility of explosion and make it a more promising and membrane-free approach. Alcohol-assisted electrocatalytic water splitting is a cost-effective approach for replacing OER with a thermodynamically favorable anodic oxidation reaction in water. Electrochemical oxidation of methanol and some biomass-derived alcohols (ethyl alcohol, benzyl alcohol, and furfuryl alcohol) show not only high performance for hydrogen production but also produce high-value products. Methanol (MeOH) is regarded as a significant C1 resource among all alcohols, with extensive applications because of its low price, great volumetric heat capacity, higher solubility in water, and outstanding oxidization reactivity. Methanol usually oxidizes to valueless CO₂ greenhouse gas (complete methanol oxidation) over electrodes in fuel cells for power generation but it is also a significant C1 raw material for formate or formic acid (HCOOH) (incomplete or selective methanol oxidation) production. Methanol costs roughly 350 euros/ton, and formic acid costs about 539 euros/ton. Apparently, industrial processes use MeOH to produce HCOOH under harsh and complex operations even utilizing toxic gas CO. Thus, it is important to attain valuable formate or HCOOH with the co-generation of hydrogen fuel through a methanol-assisted energy-saving hydrogen production process. Noble metals such as Pt, Pd, Ir, Ru, and their alloys are currently the most efficient catalysts for methanol oxidation reaction (MOR) and HER, but they are not only ineffective at selective methanol conversion into formate, but they are also highly expensive and scarce, limiting industrial-scale electrochemical methanol upgrading. Several critical challenges in the development of methanol-assisted energy-saving hydrogen production still need to be addressed such as the issue of low catalytic selectivity and efficiency towards the valuable formate product, as well as formate detection and separation.

This study aims to synthesize the self-supported interconnected porous frameworks as efficient electrocatalysts for selective conversion of methanol into formate and energy-saving hydrogen production. To achieve this goal, we used a simple, ultrafast, single-step bubble templating electrodeposition process to create mono-metallic and bimetallic interconnected porous electrodes with unique compositions and microstructures, large surface area with high catalytic potential, and tunable infrastructure.We developed the electrodeposition setup and optimized the electrolyte environment to obtain porous electrodes as well as studied the electronic and surface modifications of porous electrodes by creating the surface oxygen vacancies (Ov). Benefiting from the bimetallic synergistic effect, excellent electronic conductivity, high internal reactive surface areas, profiting electrolyte accessibility, and effective mass transfer at the electrolyte/electrode interface, these interconnected porous electrodes (NiCo@Cu, NiCu@Cu, CuCo@Ni, Ov-NiCo@Ni, and Ov-CuCo@Ni) demonstrated excellent electrocatalytic activities, selectivity and stability for integrating selective methanol oxidation to formate and energy-saving hydrogen production in alkaline conditions. Results also suggests that the synthesized porous electrodes are highly selective for the incomplete methanol oxidation (conversion of methanol to formate) and inactive for further conversion of formate to CO₂, making them highly promising catalysts for electrocatalytic methanol upgrading. The main benefit of this research is that these porous electrodes can be synthesized on a large scale due to the simple and environmentally friendly synthesis in just a couple of minutes.

Publications:

1. Farhan Arshad, Tanveer ul Haq, Adnan Khan, Yousef Haik, Irshad Hussain, Falak Sher “Multifunctional porous NiCo bimetallic foams toward water splitting and methanol oxidation-assisted hydrogen production” Energy Conversion & Management, 2022, 254, 115262. DOI. org/10.1016/j.enconman.2022.115262.

2. Farhan Arshad, Aleena Tahir, Tanveer ul Haq, Hatice Duran, Irshad Hussain, Falk Sher “ Fabrication of Ni-Cu interconnected porous nanostructures for highly selective methanol oxidation coupled with hydrogen evolution reaction” International Journal of Hydrogen Energy, 2022, 47 (85), 36118-36128. DOI. org/10.1016/j.ijhydene.2022.08.187.

3. Farhan Arshad, Aleena Tahir, Tanveer ul Haq, Akhtar Munir, Irshad Hussain, Falak Sher “Bubbles Templated Interconnected Porous Metallic Materials: Synthesis, Surface Modification, and their Electrocatalytic Applications for Water Splitting and Alcohols Oxidation” Chemistry Select, 2022, 7 (41), e202202774. DOI. org/10.1002/slct.202202774.

4. Farhan Arshad, Akhtar Munir, Aleena Tahir, Syed Zajif Hussain, Asim Jilani, Aamir Hussain, Najeeb Ullah, Falak Sher, Irshad Hussain. “Microwave-assisted growth of spherical core-shell NiFe LDH@ Cu_xO nanostructures for electrocatalytic water oxidation reaction” International Journal of Hydrogen Energy, 2023, 48 (12), 4719 – 4727. DOI. org/10.1016/j.ijhydene.2022.10.252.

5. Farhan Arshad, Tanveer ul Haq, Irshad Hussain, and Falak Sher “Recent Advances in Electrocatalysts toward Alcohol-Assisted, Energy-Saving Hydrogen Production” ACS Applied Energy materials, 2021, 4 (9), 8685–8701. DOI. org/10.1021/acsaem.1c01932.

6. Farhan Arshad, Akhtar Munir, Qasim Qayyum Kashif, Tanveer ul Haq, Javed Iqbal, Falak Sher, and Irshad Hussain. "Controlled development of higher-dimensional nanostructured copper oxide thin films as binder free electrocatalysts for oxygen evolution reaction." International Journal of Hydrogen Energy, 2020, 45 (33), 16583-16590. DOI. org/10.1016/j.ijhydene.2020.04.152.

7. Aleena Tahir, Farhan Arshad, Tanveer ul Haq, Irshad Hussain, Habib ur Rehman “Rational Design of Metal Oxide Substrate for Electrochemical Water Splitting: Recent Development and Future Perspective” ACS Applied Nano Materials, 2023, 6, 3, 1631–1647. DOI. org/10.1021/acsanm.2c04580.

8. Farhan Arshad, Aleena Tahir, Tanveer ul Haq, Hatice Duran, Irshad Hussain, Falak Sher “Electronic and Structural Modification of 3D Porous NiCo@NF as a Robust Electrocatalyst for CO₂-emission-free Methanol Upgradation to Boost Hydrogen Co-production”. (In review process)

9. Farhan Arshad, Aleena Tahir, Tanveer ul Haq, Sana Qayyum, Irshad Hussain, Falak Sher “Selective Electrochemical Methanol Upgrading and Energy-saving Hydrogen Production: A Recent Progress, Mechanistic Study and Future Directions”. (In preparation)