Water electrolysis

Abstract

Electrochemistry has the potential to sustainably transform molecules with electrons supplied by renewable electricity. It is one of many solutions towards a more circular, sustainable and equitable society. To achieve this, collaboration between industry and research laboratories is a must. Atomistic understanding from fundamental experiments and modelling can be used to engineer optimized systems whereas limitations set by the scaled-up technology can direct the systems studied in the research laboratory. In this Primer, best practices to run clean laboratoryscale electrochemical systems and tips for the analysis of electrochemical data to improve accuracy and reproducibility are introduced. How characterization and modelling are indispensable in providing routes to garner further insights into atomistic and mechanistic details is discussed. Finally, important considerations regarding material and cell design for scaling up water electrolysis are highlighted and the role of hydrogen in our society's energy transition is discussed. The future of electrochemistry is bright and major breakthroughs will come with rigour and improvements in the collection, analysis, benchmarking and reporting of electrochemical water splitting data.

Voltammetric Kinetic Studies of Electrode Reactions: Guidelines for Detailed Understanding of Their Fundamentals

“…The exercises proposed were solved by the students in an activity report sheet (see Section S2 in Supporting Information), which also included some questions relative to the manipulation of the theoretical expressions. As a complement to this short course, some bibliographic examples of the electrochemical conversion of small molecules, such as hydrogen or oxygen, in fuel cells and metal–air batteries could be discussed (see refs − ). The follow-up discussion would be focused on the characterization of the performance of the electrochemical reactions taking place, and, briefly, on the importance of the catalysis.…”

An Edible Rechargeable Battery

“…[42,43] Therefore, we find it advisable to keep the voltage of edible batteries well under 1.23 V, the minimum voltage needed for electrolysis of water. [44] During tests in which the battery was fully discharged to 0 V, the capacity in initial charging cycle was found to be 3 times higher than the discharge capacity of the subsequent cycle. In the subsequent cycles, the efficiency was rather high, 97% after 50 cycles (Figure 3f).…”

“…[ 42,43 ] Therefore, we find it advisable to keep the voltage of edible batteries well under 1.23 V, the minimum voltage needed for electrolysis of water. [ 44 ]…”

Lattice Oxygen Activation for Enhanced Electrochemical Oxygen Evolution

“…Technically speaking, compared to the cathodic molecular upgrading (e.g., hydrogen evolution or CO 2 reduction), the anodic halfreaction of oxygen evolution reaction (OER) considerably limits the overall electrical-to-chemical energy conversion efficiency owing to its sluggish kinetics. 5,8 Although Ir/Ru-based materials are the state-of-the-art OER electrocatalysts, their scarcity and high cost largely hinder the widespread implementation in the electrolysis industry. 9 To address this dilemma, chemists and material scientists have put tremendous efforts into the exploration in terms of either improving the intrinsic activity of Ir/Ru-based catalyst hosts 9 or seeking the earth-abundant transition metal (TM) alternatives.…”

“…The innovative breakthrough for the utilization of sustainable energies (e.g., solar energy and wind energy) provides the inspiring route for the modern human society to confront the daunting challenges from global energy and environmental concerns. − The electrolysis technique, represented by water splitting for green hydrogen production , and CO 2 conversion to fuels, , is an appealing choice because it can harvest the renewable electricity into value-added chemical bonds. Technically speaking, compared to the cathodic molecular upgrading (e.g., hydrogen evolution or CO 2 reduction), the anodic half-reaction of oxygen evolution reaction (OER) considerably limits the overall electrical-to-chemical energy conversion efficiency owing to its sluggish kinetics. , Although Ir/Ru-based materials are the state-of-the-art OER electrocatalysts, their scarcity and high cost largely hinder the widespread implementation in the electrolysis industry . To address this dilemma, chemists and material scientists have put tremendous efforts into the exploration in terms of either improving the intrinsic activity of Ir/Ru-based catalyst hosts or seeking the earth-abundant transition metal (TM) alternatives. , For instance, the Co element is considered as an attractive catalytic center for the OER owing to its favorable redox chemistry and structural flexibility.…”