Frustrating Surface Segregation by Nanoconfinement: Boosting Electrochemical Ozone Production over a B₁₃C₂-Encapsulated PtNi Alloy Electrocatalyst

A major challenge that limits the applications of nanostructuredelectrocatalysts is precise surface structure regulation. The criticalperformance-impeding factors for the important electrochemical ozoneproduction (EOP) lie in the leaching-induced poor stability as wellas the competing oxygen evolution and ozone production reactions overthe most promising platinum-based electrocatalysts. Although compositiondiversification by alloying appears to be a prevailing strategy tooptimize platinum-based electrocatalysts, a practical restrictionturns out to be the inevitable surface segregation and terminationof platinum-enriched structures due to their lower surface energies.In this work, we introduce the nanoconfinement of intermetallic platinum-nickelnanostructures encapsulated by boron carbide, which effectively frustratesthe surface segregation of alloy nanostructures and well maintainsthe pristine termination of the alloy. Precise atomic-level structuralelucidation and model construction of the encapsulated alloy nanostructuresare achieved by quantitative electron microscopy. The composite nanoalloywith a unique surface termination evokes synergetic catalytic effectsthat promote the charge transfer between the surface and adsorbedoxygen intermediates, which entails outstanding EOP performance witha high Faraday efficiency of 14.8% in neutral media and long-termstability of up to 120 h as a qualified electrocatalyst for the EOPelectrolyzer devices. More importantly, the current work paves a newroute to overwhelm the thermodynamically limited surface structuresof bare nanoalloy catalysts through diverse nanoconfinement strategies.