“Teaching Nature” – Nanjing University of Science and Technology realizes transformative “filmless” electrolysis of water to produce hydrogen

On July 5, 2023, the team of Professor Li Qiang and Professor Liu Dong from the School of Energy and Power Engineering of Nanjing University of Science and Technology published the research results entitled “Ampere-Level Membrane-Less Water Electrolysis Enabled by Rose-Petal-Effect-Mimetic Interface” in the journal Joule.

The results report on a revolutionary “membraneless” electrolysis of water hydrogen production unit. The bionic rose petal effect realizes “bubble-free” electrolysis of water to hydrogen at a current density of 4.2 A/cm2. Under the condition of no ion exchange membrane or diaphragm, the energy conversion efficiency of the membraneless and single-chamber electrolysis device reaches 61.5% and the hydrogen mixing rate is only 0.003% when working at 1 A/cm2. The corresponding authors of the paper are Professor Li Qiang and Professor Liu Dong; The first author is PhD student Deng Kai.

Hydrogen production from water electrolysis driven by renewable energy can produce clean hydrogen energy and achieve high-density storage of fluctuating renewable energy electricity, which is one of the important technologies to achieve the “dual carbon” goal. The hydrogen and oxygen produced by electrolysis of water become bombs if mixed together, so from the first electrolysis units in the 19th century to today’s commercial PEMs and alkaline electrolyzers, they are divided into two chambers, cathode and anode, by ion exchange membranes or diaphragms. The shackles of membranes are the key bottlenecks that are difficult to promote PEM and alkaline electrolyzers on a large scale.

In this work, the team of Professor Li Qiang and Professor Liu Dong of Nanjing University of Science and Technology “taught nature” and proposed the electrode design method of bionic rose petal effect. The electrode has both hydrophobicity and adhesion to water, like rose petals, even if the electrode is inverted water droplets will not fall, for the electrons, ions and gas molecules to build an efficient transport channel at the same time, to achieve the synergy of increasing current density, improving energy conversion efficiency, and suppressing bubbles.

Figure 1: Rose petal effect and biomimetic electrodes.

The rose petal effect biomimetic electrode (RPEM) achieved a “bubble-free” electrolyzed water hydrogen current density of up to 4.2 A/cm2 (1 M H2SO4 electrolyte). The gas diffusion electrode (GDL) and planar electrode (Planar) began to generate a large number of bubbles at 0.8 and 0.02 A/cm2, respectively. The cathode and yang electrodes use rose petal effect biomimetic electrodes at the same time, and a revolutionary “filmless” electrolysis device is developed, and when working at a current density of 1 A/cm2, the hydrogen mixing rate is only 0.003%, and the energy conversion efficiency is as high as 61.5%. While significantly reducing membrane costs, performance exceeds commercial alkaline electrolyzers and is comparable to PEM. The research results can be extended to alkaline electrolytes and low-cost catalytic materials to further reduce the cost of hydrogen production.

Figure 2: Performance of bionic electrodes and membraneless electrolyzers.

This achievement provides a new direction for the reform and large-scale promotion of electrolyzed water hydrogen production technology driven by renewable energy. This work was awarded by the NSFC “Energy Orderly Conversion” Basic Science Center Project (No. 51888103) Funding of the National Key Research and Development Program (No. 2021YFF0500700). (Source: Science Network)

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