Utilizing the Space‐Charge Region of the FeNi‐LDH/CoP p‐n Junction to Promote Performance in Oxygen Evolution Electrocatalysis

Abstract

The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p‐n junctions are constructed in 3D free‐standing FeNi‐LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi‐LDH in the space‐charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485 V (vs. RHE) of FeNi‐LDH/CoP/CC achieves ca. 10‐fold and ca. 100‐fold increases compared to those of FeNi‐LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH− has a stronger trend to adsorb on the surface of FeNi‐LDH side in the p‐n junction compared to individual FeNi‐LDH further verifying the synergistic effect in the p‐n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities.

Simultaneously Realizing Rapid Electron Transfer and Mass Transport in Jellyfish‐Like Mott–Schottky Nanoreactors for Oxygen Reduction Reaction

“…Besides, the C 1s peaks in HPCM‐5 exhibits a slight shift to lower one compared to MPCM (Figure 2e). These results further indicated that electrons transfer from Fe to N doped graphitic C at the heterojunction interfaces 6,9a,10,18. Overall, the charge regulation by Mott–Schottky effect in HPCM‐5 effectively causes electrons redistribution, forming a fast electron transfer path and enhancing ORR performance, which will be further discussed latter.…”

“…Mott–Schottky curve in Figure S12a, Supporting Information, indicated that the NG in HPCM‐5 is a p‐type semi‐conductor due to the negative slope and the flat band is 0.87 V versus Ag/AgCl 18. The flat band is similar to valence‐band maximum in p‐type semi‐conductor,28 so the top of valence‐band in NC in HPCM‐5 is calculate around 0.87 V versus Ag/AgCl (1.483 V vs RHE).…”

Bimetal Schottky Heterojunction Boosting Energy‐Saving Hydrogen Production from Alkaline Water via Urea Electrocatalysis

“…The calculated adsorption energies of CoMn/CoMn 2 O 4 for CO(NH 2 ) 2 and H 2 O are −2.2 and −3.57 eV, much lower than those of pristine CoMn 2 O 4 (Figure 5b), confirming the Schottky barrier region can enhance the adsorption probability and stability of urea and water molecules, namely, CO(NH 2 ) 2 and H 2 O have stronger trend to be adsorbed on the surface of the CoMn 2 O 4 side of CoMn/CoMn 2 O 4 Schottky heterostructure than the pure CoMn 2 O 4 , which is beneficial for the oxidation reaction. [ 45,47 ] Furthermore, the generated N 2 can be released more easily from the CoMn/CoMn 2 O 4 surface rather than the CoMn 2 O 4 surface due to the higher adsorption energy. Combining the catalytic mechanism analysis, these calculation results suggest that CoMn/CoMn 2 O 4 has an optimal electronic structure as a UOR catalyst.…”

2D Layered Double Hydroxide Nanosheets and Their Derivatives Toward Efficient Oxygen Evolution Reaction

“…Besides the advantages of this 3D hierarchical binder-free structure, the abundant multimetallic catalytic sites of NiCoP and NiFe LDH promote the OER activity. Qian et al proposed a concept for promoting the catalytic activities for OER by constructing the FeNi-LDH/CoP/carbon cloth (CC) heterojunctions [125]. The self-supporting FeNi-LDH/CoP/CC electrode with an open and 3D hierarchical p-n junction structure is prepared through three steps including the electrodeposition of Co(OH) 2 nanosheets array on the CC, phosphatization of Co(OH) 2 , and electrodeposition of amorphous FeNi-LDH layers on the formed CoP array ( Fig.…”