Electronic regulation of electrochemical reconstruction via a Ce3+/Ce4+ electron buffer for efficient alkaline water splitting

Ce 3+ /Ce 4+ redox drives stable β-NiOOH formation in NiCe NDC. • Ce 4f reservoirs tune Ni d-band center, lowering OER barrier. • NiCe NDC/CP exhibits good OER activity and long-term stability. • 20 MW electrolyzer assessment predicts H₂ cost ∼USD 5.40 kg −1 . The rational regulation of electrochemical reconstruction is a promising route to high-performance oxygen evolution reaction (OER) electrocatalysts, yet the underlying electronic mechanisms and their technological relevance remain elusive. Herein, a Ce-doped Ni-based metal organic framework (NiCe NDC) precatalyst is fabricated via a facile one-step solvothermal method. The reversible Ce 3+ /Ce 4+ redox pair acts as a dynamic electron-buffering center, and the strong Ni 3d–O 2p–Ce 4f orbital coupling induces controllable reconstruction into stable β-NiOOH, while inhibiting the over-oxidation and structural deterioration of active phases. In situ Raman spectroscopy and X-ray photoelectron spectroscopy verify the optimized reconstruction kinetics and reversible Ce valence evolution, while density functional theory (DFT) calculations confirm that near-Fermi-level Ce 4f states serve as electron reservoirs to modulate the Ni d-band center, enrich electronic density at the Fermi level, and reduce the free-energy barrier of the rate-determining *O to *OOH step. Optimized NiCe NDC delivers superior alkaline OER performance with a low overpotential of 194 mV at 10 mA cm −2 , a small Tafel slope of 61.8 mV dec −1 , and long-term stability over 100 h at 100 mA cm −2 . Coupled with a Pt/C cathode, the assembled overall water-splitting electrolyzer achieves current densities of 10–1000 mA cm −1 under low cell voltages of 1.42–1.90 V. A techno-economic assessment (TEA) of a 20 MW alkaline electrolyzer estimates a levelized cost of hydrogen (LCOH) of ∼USD 5.40 kg −1 H₂. This work reveals the electronic mechanism of rare-earth-regulated reconstruction and provides a feasible strategy for designing advanced OER catalysts toward industrial green hydrogen production. A rare-earth doped Ni-based MOF pre-catalyst is rationally developed for efficient alkaline OER, where Ce dopant with reversible Ce 3+ /Ce 4+ redox property acts as a dynamic electron pump to regulate the electrochemical reconstruction process and stabilize the derived active NiCeOOH phase. Enabled by this electronic modulation strategy, the resulting catalyst exhibits outstanding OER performance with an ultralow overpotential of 194 mV at 10 mA cm −2 , coupled with robust long-term durability over 100 h at a large current density of 100 mA cm −2 . Download: Download high-res image (109KB) Download: Download full-size image