The Synergistic Activation of Ce‐Doping and CoP/Ni₃P Hybrid Interaction for Efficient Water Splitting at Large‐Current‐Density

Abstract

The high intermediate (H*, OH*) energy barriers and slow mass/charge transfer increase the overpotential of alkaline water electrolysis at large‐current‐density. Engineering the electronic structure with the morphology of the catalyst to reduce energy barriers and improve mass/charge transportation is effective but remains challenging. Herein, a Ce‐doped CoP nanosheet is hybrid with Ni3P@NF (Ni foam) support to enhance mass/charge transfer, tune energy barriers, and improve water‐splitting kinetics through a synergistic activation. The engineered Ce0.2‐CoP/Ni3P@NF cathode exhibits an ultralow overpotential (η500, η1000) of −185, and −225 mV at −500 and −1000 mA cm−2 in 1.0 m KOH, along with an excellent pH‐universality. Impressively, an electrolyzer using the Ce0.2‐CoP/Ni3P@NF cathode can afford 500 mA cm−2 at a cell voltage of only 1.775 V and maintain stable electrolysis for 200 h in 25 wt% KOH (50 °C). Characterization and density functional theory calculation further reveal the Ce‐doping and CoP/Ni3P hybrid interaction synergistically downshift d‐band centers (εd = −2.0 eV) of Ce0.2‐CoP/Ni3P to the Fermi level, thereby activate local electronic structure for accelerating H2O dissociation and optimizing Gibbs free energy of hydrogen adsorption (∆GH*).

Construction of Co2P‐Ni3S2/NF Heterogeneous Structural Hollow Nanowires as Bifunctional Electrocatalysts for Efficient Overall Water Splitting

“…The Δ G H* value closer to 0 eV indicates the dynamic equilibrium [ 43 ] between the proton reduction and the desorption of H* from the active sites, thus lowering the H* adsorption/desorption energy barriers for the HER. [ 11 ] The calculation result shows that the Co 2 P (Δ G H* = −0.499 eV) and Ni 3 S 2 (Δ G H* = −0.225 eV) have stronger hydrogen binding energies than that of the Co 2 P/Ni 3 S 2 heterojunction surfaces. The reduced Gibbs free energy of Co 2 P/Ni 3 S 2 heterojunction surfaces (Δ G H* = −0.163 eV) is closer to 0 eV, indicating that the electronic interaction of the heterojunction between Co 2 P and Ni 3 S 2 weakens the H* adsorption and benefits the desorption process, thus improving the HER kinetics.…”

“…The reduced Gibbs free energy of Co 2 P/Ni 3 S 2 heterojunction surfaces (Δ G H* = −0.163 eV) is closer to 0 eV, indicating that the electronic interaction of the heterojunction between Co 2 P and Ni 3 S 2 weakens the H* adsorption and benefits the desorption process, thus improving the HER kinetics. [ 11 ] Figures S21–S23 (Supporting Information) describes the top‐view and side‐view of the adsorption geometries of OH*, O*, and OOH* on Co 2 P (211), Ni 3 S 2 (122), and Co 2 P/Ni 3 S 2 heterojunction surfaces. Based on these optimized geometries, the Gibbs free energies of these oxygen‐containing intermediates are calculated, shown in Figure 6b and Table S5 in the Supporting Information.…”

Tip effect assisted high active sites for oxygen evolution reaction tuned using transition metals (Cr, Fe and Mo) doped with CoP

“…S6b and Table S3 †). 16,17 Co-P peaks exhibited a negative shi aer Cr and Fe doping, illustrating that the CoP gained electrons from the dopants. The high electronegative Mo atom gained electrons from the Co atom, causing positive shiing of the Co-P bond.…”

Surface and near-surface engineering design of transition metal catalysts for promoting water splitting

“…16 Therefore, there is an urgent need to develop highly efficient water electrolysis catalysts. 17,18 Transition metal-based materials, such as transition metal oxides, [19][20][21] sulfides, [22][23][24] nitrides, 25 and phosphides, 26 have been widely used for catalyzing water splitting owing to their high theoretical catalytic activity. To further enhance the performance to satisfy the practical application requirements of water electrolysis, extensive efforts have been made to optimize the surface state and near-surface environment of transition metal catalysts.…”