No abstract

The discovery of acid-stable, active, and affordable electrocatalysts for the oxygen evolution reaction (OER) is crucial for the advancement of energy conversion and storage technologies to achieve a sustainable energy future. To date, the best performing electrocatalysts for OER in acidic solutions, IrO 2 and RuO 2 , are expensive and scarce. Herein, we develop a systematic theoretical framework to investigate the OER activity performance of diverse and complex acid-stable oxides. By determining the most stable oxide surfaces, accounting for realistic surface coverages under OER conditions, and using theoretical OER overpotential as an activity descriptor, we identified Co(SbO 3 ) 2 , CoSbO 4 , Ni(SbO 3 ) 2 , Fe(SbO 3 ) 2 , FeSbO 4 , FeAg(MoO 4 ) 2 , MoWO 6 , and Ti(WO 4 ) 2 as promising materials, some of which have already been experimentally found to have good OER performance, and some are new for experimental validation, thus expanding the chemical space for efficient OER materials. On the basis of the activity analysis, we further discuss strategies to improve the OER catalytic activity and the remaining challenges.

Alloying is a powerful tool that can improve the electrocatalytic performance and viability of diverse electrochemical renewable energy technologies. Herein, we enhance the activity of Pd-based electrocatalysts via Ag-Pd alloying while simultaneously lowering precious metal content in a broad-range compositional study focusing on highly comparable Ag-Pd thin films synthesized systematically via electron-beam physical vapor co-deposition. Cyclic voltammetry in 0.1 M KOH shows enhancements across a wide range of alloys; even slight alloying with Ag (e.g. Ag0.1Pd0.9) leads to intrinsic activity enhancements up to 5-fold at 0.9 V vs. RHE compared to pure Pd. Based on density functional theory and x-ray absorption, we hypothesize that these enhancements arise mainly from ligand effects that optimize adsorbate–metal binding energies with enhanced Ag-Pd hybridization. This work shows the versatility of coupled experimental-theoretical methods in designing materials with specific and tunable properties and aids the development of highly active electrocatalysts with decreased precious-metal content.

C–O activation is a crucial step in Fischer–Tropsch synthesis (FTS). Several pathways have been proposed to activate CO, namely, direct C–O dissociation, activation via hydrogenation, and activation by insertion into growing chains. Invariably, very high barriers are calculated for both direct C–O dissociation and for hydrogenation at the O atom in CO* and RCO*, while hydrogenation at the C atom leads to oxygenates. We demonstrate that surface hydroxyl groups open a new pathway for CO* and RCO* activation via proton transfer to the O atom. In combination with the CO insertion mechanism, the calculated rate for this new pathway is consistent with the selectivity in FTS, and is in agreement with the kinetic effect of water. Hydroxyl group formation from O* is sufficiently fast to be quasi-equilibrated, and is much faster than CO2 formation. The role of surface hydroxyl groups as hydrogenating species is likely general, and involved in several oxygenate transformation reactions.

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.