CNRS Chemistry welcomes Viola Birss as the Ambassador in Chemical Sciences

• Considerable effort is focused on developing electrochemical materials for energyapplications. Can you tell us more about your team's work in this field?

My team's efforts are focused on the development of electrocatalytic materials, especially for fuel cells and electrolysis cells, which can operate either at low temperatures (so-called PEM systems when under acidic conditions) or at high temperatures (solid oxide systems).  While catalyst composition is the most critical parameter that must be optimized, porosity is also an important factor, as it increases the active surface area at which electrochemical reactions take place resulting in greater efficiency. However, the pore properties must be optimized in order to maximize the diffusion of gaseous reactants such as H₂ and O₂, as well as ions, to/from the catalytic sites, which in turn, results in higher power and energy output. 

For low-temperature PEM fuel cells, we are developing a new family of nanoporous carbon supports, ranging from powders (CIC) to free-standing scaffolds, or sheets (NCS). Our aim is to control their internal nanoporosity to produce either monodisperse 3D interconnected pores (10 to 200 nm) or bimodal or multimodal pores to overcome some of the problems posed by current carbon powders. Another advantage of these materials is that they have a high concentration of surface defects that facilitate the nucleation and stabilization of heteroatomic dopants and metal nanoparticles for catalytic applications.  For example, after doping with nitrogen, our nanoporous carbons become catalytic for CO₂ reduction in aqueous media. Better still, a second doping with Fe or Ni atoms further increases the catalytic activity while also significantly enhancing product selectivity and catalyst durability. Furthermore, the NCS scaffolds are ideal for atomic layer deposition of nanoparticles, such as Pt, leading to excellent cathode performance in PEM fuel cells. All of these materials can also be used as electrodes in redox flow batteries and supercapacitors, as the uniformity and 3-dimensional interconnectivity of the nanopores, combined with the good surface wettability, allow the electroyte to access the full internal carbon surface area.

For solid oxide fuel cells operating at high temperatures, we are developing a family of mixed conducting metal oxide catalysts. We have demonstrated that these new materials are capable of catalyzing both H₂ oxidation and O₂ reduction at high power densities and excellent stability, with lowered manufacturing costs resulting from the cell symmetry. These catalysts can also be used at both electrodes during electrolysis, converting CO₂ to CO, steam to H₂, or CO₂+steam to synthesis gas at the cathode, while generating  pure O₂ at the anode.  Operating at high temperatures, these electrodes are proving to be extremely efficient, easily generating 1 W/cm2 at cell voltages of around 1.5 V, far exceeding (by factors of 2 to 3) what is achievable in low temperature electrolysis cells. We are also seeking to optimize our materials for the direct conversion of natural gas to clean electricity and heat, while simultaneously capturing the CO₂ produced at the anode and storing it for future use.

• What progress can we expect in this area over the next few years?

The hope is that we can rapidly move towards a cleaner energy future by taking advantage of a wide range of electrochemical technologies.  The situation is urgent given the many current negative impacts on our planet associated with hydrocarbon combustion and CO₂ emissions. Although scientists are making significant progress in improving device performance, reducing costs, enhancing lifetimes, etc., the development and implementation of electrochemical technologies needs to be accelerated. If we are to have any hope of bringing these devices to market, this urgently requires robust government policy and assistance to the sectors involved in the manufacture and development of fuel cells, electrolysis cells, batteries, etc,.  In addition, we urgently need to put in place the H₂ infrastructure required for the widespread use of hydrogen as an energy carrier in all countries.

Specifically, we need to accelerate the implementation of fuel cells in long-distance road transport and railway applications which are now beginning to appear. If the infrastructure for distributing H₂ fuel (filling stations) were rapidly put in place, this would immediately boost the production and use of fuel cell operated vehicles using H₂ as the energy source.  As the product of the reactions involved in PEM fuel cells is pure water, this would be a major step forward in eliminating harmful combustion products such as CO₂, produced currently at massive volumes in today's transportation sector.  So-called “solid oxide” fuel cells, which operate at higher temperatures (between 600 and 800°C), are more likely to find application in stationary settings. But here again, large-scale development will require the setting of appropriate government policy and the support of public authorities. 

• As Ambassador for Chemical Sciences in France, do you have any particular expectations of this upcoming tour? 

I'm looking forward to meeting many CNRS scientists and engineers who are conducting research in the field of electrochemistry and clean energy conversion/storage.  My aim is to share and exchange knowledge and ideas, leading to new collaborative research that could, I hope, result in major advances in the performance and/or implementation of electrochemical technologies for the energy transition. I'm also looking forward to meeting and talking with students, while also learning how CNRS works and how it organizes and stimulates collaboration between laboratories. Finally, I'm hoping to meet other members of the H₂ France/Canada international network, of which I'm a member, to formalize common research topics around which we can build longer-term collaborations.