Atom Walls Confined Hyperdispersed Pt Nanocrystal Electrocatalysts for a Photovoltaic-Integrated Energy Storage System.

Platinum-based catalysts are widely used in catalysis and energy storage; however, their reaction activity is often compromised by the formation of large agglomerates during nanoparticle growth. In this study, we constructed "TiOx atomic walls" (TOAWalls) on multiwalled carbon nanotubes using a rotating chamber atomic layer deposition system, a method scalable to the tens-of-grams level. These uniformly dispersed TOAWalls effectively confine platinum nanoparticle growth, yielding highly dispersed platinum nanocrystals (∼2.4 nm) with an interparticle spacing of 1.8 nm, even at a tunable loading as low as 5.2 wt %. Concurrently, the TOAWalls induce electronic charge redistribution, thereby strengthening the coupling between the oxygen atoms and platinum metal sites. Attributed to the synergistic effect of atomic wall confinement and Pt-O coordination, this electrocatalyst exhibited stable performance over 100 h of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). When employed as a cathode in liquid zinc-air batteries, it yielded a power density of 277 mW cm-2 and sustained stable cycling performance for over 365 h, extending to 480 h in planar cell configurations. Capitalizing on the catalyst's multifunctionality, we demonstrate an integrated photovoltaic-energy storage and hydrogen production system; this setup facilitates around-the-clock water-splitting by coupling flexible zinc-air batteries with photovoltaic power generation.