Unique Step‐Scheme Heterojunction Photoelectrodes for Dual‐Utilization of Light and Chemical Neutralization Energy in Switchable Dual‐Mode Batteries

Abstract

AbstractHere, a unique step‐scheme (S‐scheme) heterojunction array involving C4N and aligned TiO2 nanorods, namely C4N@TiO2NR, is explored as an advanced photoelectrode for developing an innovative acid–base/Zn–air hybrid cell capable of harvesting light and chemical neutralization energy (CNE) in one integrated system to boost the charge/discharge performance. The properly staggered band arrangement with a built‐in electric field in C4N@TiO2NR induces an S‐type charge migration path to ensure superior redox ability of photogenerated carriers with efficient spatial separation. This coupled with the structural merits of 3D hierarchical arrays enables remarkable photocurrent response and facilitates oxygen evolution kinetics upon irradiation. Paring this heterojunction photoelectrode with an alkaline Zn electrode and an acidic air electrode produces a light and CNE dual‐assisted cell with two switchable modes of light‐assisted acid‐base/air battery (LABAB) and acid‐base battery (LAB). By capturing light during charge and CNE during discharge, LABAB breaks the limit of the equilibrium potential (1.65 V) of conventional Zn–air batteries (ZABs) to deliver impressive charge/discharge voltages of 0.43/2.02 and 0.87/1.86 V at 0.1 and 10 mA cm−2, superior to all reported ZABs. respectively. When LABAB is switched to LAB, it can harvest light and CNE simultaneously to afford markedly increased output voltage relative to common acid–base batteries.