Acceptor‐Doping Accelerated Charge Separation in Cu₂O Photocathode for Photoelectrochemical Water Splitting: Theoretical and Experimental Studies

Abstract

Cu 2 O is a typical photoelectrocatalyst for sustainable hydrogen production, while the fast charge recombination hinders its further development. Herein, Ni 2+ cations have been doped into a Cu 2 O lattice (named as Ni-Cu 2 O) by a simple hydrothermal method and act as electron traps. Theoretical results predict that the Ni dopants produce an acceptor impurity level and lower the energy barrier of hydrogen evolution. Photoelectrochemical (PEC) measurements demonstrate that Ni-Cu 2 O exhibits a photocurrent density of 0.83 mA cm À2 , which is 1.34 times higher than that of Cu 2 O. And the photostability has been enhanced by 7.81 times. Moreover, characterizations confirm the enhanced light-harvesting, facilitated charge separation and transfer, prolonged charge lifetime, and increased carrier concentration of Ni-Cu 2 O. This work provides deep insight into how acceptordoping modifies the electronic structure and optimizes the PEC process. Developing hydrogen energy plays a critical role in revolutionizing the current fossil-fuel-based energy system. [1] In various sustainable hydrogen production routes, photoelectrochemical (PEC) water splitting has drawn increasing attention since 1972. [2] Numerous materials, including Si, [3] g-C 3 N 4 , [4] metal oxides, [5] metal-chalcogenides, [6]

Inversely Tuning the CO2Electroreduction and Hydrogen Evolution Activity on Metal Oxide via Heteroatom Doping

“…36-1451) (Figure 2 a), while a slight peak shift appears in the modified ZnO (Supporting Information, Figure S2b), suggesting a homogeneous incorporation of heteroatoms. [11] Similar morphologies and lattice fringes are observed on the scanning and transmission electron microscope images ( Figure S5e). It is difficult to clearly distinguish Mo/Cu from Zn owing to their relatively light atomic mass.…”

“…[7] Altering the electronic states near the Fermi level of catalysts is proved to regulate the reaction kinetics of metal oxides for hydrogen evolution and oxygen evolution. [8,11] However, during the practical CO 2 RR electrolysis, CO 2 RR and competing hydrogen evolution reaction (HER) will simultaneously proceed and synergistically determine the practical CO 2 RR performance. [9] Although fundamentally comparing the HER and CO 2 RR has been applied in designing efficient metal-based CO 2 RR catalysts, [10] the current theoretical analysis for most metal oxides are limited to the CO 2 RR without considering HER.…”

Highly Efficient InGaN Nanorods Photoelectrode by Constructing Z‐scheme Charge Transfer System for Unbiased Water Splitting

“…The main peaks of Cu 2p 3/2 and Cu 2p 1/2 at 932.06 and 951.86 eV in InGaN/Cu 2 O are ascribed to Cu + , where the binding energies have a downshift than that of Cu 2p in Cu 2 O (Figure 2b). [ 26 ] It may be attributed to the migration of the electron from InGaN to Cu 2 O, which can provide a definite evidence for charge transport of InGaN/Cu 2 O heterojunction. Moreover, two satellites for Cu 2p spectra reveal the trace of Cu 2+ , which has a positive effect on PEC performance as demonstrated by some works.…”

“…However, N1s peaks of InGaN/Cu 2 O show a slight upshift compared to that of pure InGaN, which further provids the evidence for the electron transfer from InGaN to Cu 2 O (Figure 2f). [ 26 ]…”

“…Exploring suitable semiconductor with energy band alignment to InGaN is the key issue to fabricate Z-scheme InGaN heterostructure. Cu 2 O is one of the most attractive photocathode materials owing to its direct bandgap (≈2.0 eV) for visible-light response and favorable conductive band edge potential, [26,27] which is expected to become a promising candidate to match InGaN nanorods. Recently, Cu 2 O has been successfully supported on various metal oxides such as Ga 2 O 3 , WO 3 and BiVO 4 to build type-II heterostructure photoanodes.…”