Bio-inspired Hydrogen Generation by Novel Bubble-Free Electro-Catalytic Systems

February 20th, 2023

R&D Focus Areas:
Electrolysis, Photochemical and photocatalytic processes

Lead Organisation:
Australian National University (ANU)

University of Wollongong


Start date:
July 2019

Completion date:
March 2022

Key contacts:
Emeritus Professor Robert Stranger:
Professor Gerhard Swiegers:
Associate Professor Takuya Tsuzuki:

ARENA: AUD$615,682 (2019-2022)

Project total cost:

Project summary description:
Many non-fossil fuel energy production methods (solar, wind etc.) yield electricity but are fundamentally intermittent. Hydrogen is recognized as the ideal clean, high capacity, chemical medium for storage of energy from non-constant sources, capable of achieving stable energy continuity. Electrolytic hydrogen generation, using cheap and abundant inputs (sunlight and water) is the preferred approach, if the process can be made sufficiently economical and energy efficient.

A future hydrogen economy will likely depend on hydrogen produced by water electrolysis using renewable energy. Renewable, or green, hydrogen may find applications in seasonal storage, as a transportation fuel, and as a chemical feedstock. It is likely that a low-cost, energy-efficient electrolyser will form an important part of a future hydrogen economy.

Electrolysis of water involves passing an electric current through a water solution, by means of two electrodes. The positive electrode generates oxygen (O2) and the negative electrode generates hydrogen (H2). The process is well known, but presently suffers from two major difficulties:

i) The formation of hydrogen and oxygen bubbles during traditional electrolysis represents an impediment to the realisation of low-cost, energy-efficient electrolysers. Bubbles require energy to form, and partially block electrode surfaces, reducing the active area available for gas evolution reactions. Furthermore, the gases generated at the two electrodes must be separated from solution. The problem of bubble coverage is typically overcome by pumping liquid over the electrodes. However, pumps add to system cost, lower system efficiency due to their power consumption, require maintenance, and compromise reliability. Furthermore, the bubble-laden liquids must be piped to gas-liquid separators. Thus, bubbles not only reduce the energy efficiency of electrolysers, but they also add significant cost and complexity to their design, fabrication, operation, and maintenance.

ii) Another impediment to the realisation of low-cost, energy-efficient electrolysers is the traditional use of strongly acidic or strongly alkaline electrolytes necessitating the use of expensive, high-quality materials such as Pt electrodes due to the corrosive environment. Since biochemical reactions in nature mostly occur at mild pH, the pursuit of biomimicry would permit the use of cheaper, lower quality materials. With these impediments in mind, the project aimed to use biologically inspired catalysts with gas permeable electrode surfaces to develop a simpler and more efficient hydrogen generating electrolysis technology than any known to operate from pure water and renewable electricity. Of relevance is the well-known, naturally occurring Oxygen Evolving Complex (OEC) within Photosystem II (PSII) which contains a Mn4CaO5 cluster that catalyses the oxidation of water to oxygen. The development of oxygen evolution electrocatalysts based on Earth-abundant Mn and Ca has been motivated by the high activity and low overpotential of the Mn4CaO5 cluster for the oxidation of neutral water.

The objective was to develop high performance catalysts with components that mimic those of the natural water oxidation catalyst of photosynthesis, namely, the OEC. These were then to be deposited on specially designed gas permeable electrodes to achieve ‘bubble-free’ water splitting in the same way that occurs in photosynthesis. The hypothesis was that such a system should offer a more efficient hydrogen generating electrolysis technology than any known to date using water of near-neutral pH. The ability to avoid the very high or low pH’s normally required in water electrolysers offers a potentially important commercial advantage in green hydrogen production. For example, it allows green hydrogen production without notable corrosion.

The project has successfully demonstrated the hypothesis on which it was based, namely, that an Earth-abundant, bio-inspired catalyst undertaking bubble-free hydrogen generation could convert near-neutral water into hydrogen at low energy. The final outcome of the project has been the development of a prototype – a highly efficient, multi-cell hydrogen generating electrolyser (16 cm2 electrodes in each cell) at Technology Readiness Level (TRL) 4, operating from water under mild chemical conditions and employing low-cost abundant-earth materials. The prototype allows for a detailed analysis of the commercial potential of the technology, including product costings, business model and preliminary market assessment, which will be carried out next by the chief investigators.

Related publications and key links:

  1. a) Journal Publications

1) A. Gagrani, M. Alsultan, G. F. Swiegers, T. Tsuzuki, Photo-Electrochemical Oxygen Evolution Reaction by Biomimetic CaMn2O4 Catalyst, Applied Sciences, 2019, 9, 2196-2206.

2) A. Gagrani, M. Alsultan, G. F. Swiegers, T. Tsuzuki, Comparative Evaluation of the Structural and Other Features Governing Photo-Electrochemical Oxygen Evolution by Ca/Mn Oxides, Catalysis Science and Technology, 2020, 10, 2152-2164.

3) R. N. L. Terrett, G. Tsekouras, T. Tsuzuki, G. F. Swiegers, R. J. Pace, R. Stranger, Electronic Structure Modelling of Edge-Functionalisation of Graphene by MnOx Particles, R. Terrett, Physical Chemistry Chemical Physics, 2020, 23 (1), 514-527.

4) G. Tsekouras, R. N. L. Terrett, Z. Yu, Z. Cheng, G. F. Swiegers, T. Tsuzuki, R. Stranger, R. J. Pace, Insights into the Phenomenon of ‘Bubble-Free’ Electrocatalytic Oxygen Evolution from Water, Sustainable Energy and Fuels, 2021, 5, 808-819.

5) G. Tsekouras, R. N. L. Terrett, A. Walker, Z. Yu, Z. Cheng, D. L. Officer, G. G. Wallace, G. F. Swiegers, T. Tsuzuki, R. Stranger, R. J. Pace, Interaction of graphene, MnOx, and Ca2+ during biomimetic, ‘bubble-free’ electrochemical oxygen evolution at mild pH, International Journal of Hydrogen Energy, 2021, 46, 28397-28405.

6) G. F. Swiegers, R. N. L. Terrett, G. Tsekouras, T. Tsuzuki, R. J. Pace, R. Stranger, The Prospects of Developing a Highly Energy-Efficient Water Electrolyzer by Eliminating or Mitigating Bubble Effects, Sustainable Energy and Fuels, 2021, 5, 1280-1310.

7) R. N. L. Terrett, G. Tsekouras, T. Tsuzuki, G. F. Swiegers, R. J. Pace, R. Stranger, Towards a Computational Understanding of Water Oxidation at Graphene-Bound MnxOy and MnxOyM2+ Particles, Sustainable Energy Fuels, 2022. 6, 2276-2288

  1. b) Papers Submitted for Publication

8 D. Boskovic, R. N. L. Terrett, M. S. M. Basheer, P. Wagner, R. J. Pace, R. Stranger, G. F. Swiegers, A bioinspired water oxidation catalyst that is approximately one-tenth as active as the Photosystem II Oxygen Evolving Center at neutral pH.

9) G. Tsekouras, R. N. L. Terrett, G. Ryder, A. Walker, A. Hodges, A. L. Hoang, C-Y. Lee, K. Wagner, Z. Yu, D. L. Officer, G. G. Wallace, G. F. Swiegers, T. Tsuzuki, R. Stranger, R. J. Pace, A 16 cm2, two-cell, biomimetic, ‘bubble-free’, ‘capillary-fed’ water electrolyser operating at mild pH.

  1. c) Patent Applications

Patent title “Biomimetic Water Oxidation Catalysts” (Pace et al., International PCT patent application WO2019119044 which was filed in the USA as US Patent Application 16/955997 on 23 June 2020)

Higher degree studies supported:
Not applicable


February 2023