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]

Progressively stimulating carrier motion over transient metal chalcogenide quantum dots towards solar-to-hydrogen conversion

“…It should be noted that the bandgap values are smaller than that obtained via DRS results, which is mainly ascribed to the fact that the band gaps derived from DFT calculation are usually underestimated. 54–57 As shown in Fig. 4(c and f), introducing Ni dopant endows the CdSe QDs with an obviously increased DOS at the valence band maximum (VB M ) with respect to the pristine CdSe QDs, guaranteeing the presence of more charge carriers in the composite photocatalyst.…”

Stability of Photocathodes: A Review on Principles, Design, and Strategies

“…found that an acceptor impurity level occurred under conduction band of Cu 2 O and the band gap narrowed down, promoting generation and separation of photocarriers (Figure 15e). [95] Lastly, the energy barrier of hydrogen evolution was lowered, and the photostability of dopped Cu 2 O increased by 7.81 times than the pure Cu 2 O (Figure 15f). Similarly, the research suggests that Zn dopant contributed to improving carrier concentration and charge transfer.…”

Imperfect makes perfect: defect engineering of photoelectrodes towards efficient photoelectrochemical water splitting

“…185 For instance, the Ni 2+ cation was doped on the surface of Cu 2 O (Ni-Cu 2 O) by a hydrothermal method. 186 Ni acceptor doping can transfer the electrons in Cu and O to Ni, promoting the redox reaction rate and greatly enhancing the PEC performance (Fig. 15a-d).…”