Tuning electrochemically driven surface transformation in atomically flat LaNiO3 thin films for enhanced water electrolysis

Carbonate formation lowers the electrocatalytic activity of perovskite oxides for water electrolysis

“…XPS investigation aer storage in UHV (p tot # 2 Â 10 À9 mbar) for $40 h and UHV transfer to the analysis chamber conrms that the LaNiO 3 thin lms are Ni-terminated (see ref. 12) and free of adsorbed contaminants except for a thin layer of adventitious carbon, as expected for a UHV transfer system (Fig. 2).…”

“…This glove box contained a N 2 atmosphere (CO 2 partial pressure $5 ppm) with a constant stream of pure N 2 gas and hosted a rotating disc electrode setup specically modied for the study of single crystalline samples. 12,23 Aer electrochemical characterization, the sample was thoroughly rinsed with deionized water (Milli-Q, R > 18 MU cm), dried, remounted into the UHV sample holder and inserted into the clean transfer vessel. Importantly, the samples are mounted without the frequently applied silver paste and tested electrochemically without the need for epoxy coverage, 24,25 further minimizing possible contamination sources.…”

“…[8][9][10] Epitaxial thin lms allow investigation of oxide catalysts fabricated with unit-cell precision. 11 Recently, we used epitaxial LaNiO 3 layers to demonstrate the important role of the surface terminating layer composition, 12 an activity descriptor that is difficult to recognize in catalysts fabricated using traditional routes. 13,14 Beyond the intrinsic oxide surface composition, surface contaminants may alter the catalyst surface composition and electronic properties, as has been demonstrated extensively at solid/gas interfaces, where trace amounts of CO, CO 2 , and H 2 S are "poisonous" for fuel cell operation.…”

“…These carbonate groups are thermodynamically stable, 22 block the active sites, and ultimately prevent the formation of the active Ni oxyhydroxide surfaces. 12 Understanding the deactivation of surfaces by air exposure has important implications for technological applications of transition metal oxide catalysts.…”

Electrocatalysis for the Oxygen Evolution Reaction in Acidic Media: Progress and Challenges

“…Converting their energy to a zero-emission chemical energy carrier such as hydrogen is an alternative that can achieve versatile utilization, such as clean heating or electricity at a later stage, on account of the high energy density of hydrogen [5,[10][11][12]. Therefore, an increasing number of sustainable pathways for energy conversion and storage technologies, including water electrolysis, batteries, and fuel cells, have been proposed and extensively investigated [5,[13][14][15]. Proton exchange membrane water electrolysis (PEMWE) operating in acidic environments has offered an effective way to produce sustainable, high-purity hydrogen through targeted electrochemical reactions since the 1960s [16] (Figure 1).…”