Rational Design and Characterization of Direct Z-Scheme Photocatalyst for Overall Water Splitting from Excited State Dynamics Simulations

Abstract

Direct Z-scheme heterostructure photocatalysts possess tremendous potential to solar-driven overall water splitting, but how to rationally design and comprehensively characterize high-efficient direct Z-scheme heterostructures remains a great challenge. Herein, we report the design of metal-free C3B/C3N heterostructure through constructing a p-n heterojunction as a potential direct Z-scheme photocatalyst for overall water splitting by combining first-principles and excited state dynamics simulations. Our calculations show that the strong interlayer interaction in C3B/C3N p-n heterostructure provides a large built-in electric field with about 0.4 V/Å and strong interface nonadiabatic coupling which significantly accelerates the recombination of carriers with weak redox capacity (∼0.5 ps) and retards the lifetime of carriers with strong redox capacity (∼4 ps). Meanwhile, the B atoms, serving as Lewis acid sites, are good catalytic centers to trap water molecules. The hydrogen reduction reaction and complex four-electronic water oxidation reaction can happen smoothly on the C3B and C3N surface, respectively, without additional overpotential and cocatalyst. This work not only provides a potential metal-free direct Z-scheme photocatalyst for overall water splitting, but also paves the way to rational design high-performance direct Z-scheme photocatalysts.