Preparation and Economic Analysis of High-current-density Electrocatalysts for Alkaline Water Electrolysis

doi:10.15541/jim20250012

Abstract

Abstract:

Alkaline water electrolysis (AWE) faces challenges of low efficiency and high costs due to its relatively low current density. It is necessary to develop efficient and stable non-precious metal electrocatalysts under high current densities. In this study, an amorphous NiMoOP/NF electrocatalyst was fabricated by the hydrothermal method combined with phosphorization on a nickel foam (NF) substrate. The amorphous needle-like morphology effectively increases active sites and enhances the stability of hydrogen production through water electrolysis. At current densities of 10 and 1000 mA·cm^-2, the hydrogen evolution overpotentials are 31 and 370 mV, respectively, and the catalyst stably runs for 1100 h at a high current density of 1 A·cm^-2. The NiMoOP/NF material, when integrated with crystalline silicon heterojunction solar cells for overall water splitting, achieves a theoretical solar-to-hydrogen conversion efficiency of up to 18.60%. Under industrially relevant conditions (60 ℃, 30% (in mass) KOH electrolyte), the electrolysis voltage is 1.77 V, enabling a current density of 400 mA·cm^-2, with a hydrogen production energy consumption of 4.19 kWh·Nm^-3 (Nm³: Normal cubic meter). Economic analysis of photovoltaic-powered hydrogen production via electrolysis indicates that the minimum hydrogen production cost for an off-grid and non-storage photovoltaic hydrogen production system is ¥28.52 kg^-1. The amorphous nanoneedle-like materials developed in this study significantly enhanced both hydrogen evolution activity and stability during water electrolysis, providing valuable insights for design of high-current-density hydrogen evolution catalysts. Furthermore, the combined economic analysis of photovoltaic electrolysis for green hydrogen production supports advancement of green hydrogen industry.

Key words: water electrolysis for hydrogen production, amorphous design, high current density, economic analysis, levelized cost of hydrogen

CLC Number:

TQ116

YU Zelong, TANG Chun, RAO Jiahao, GUO Heng, ZHOU Ying. Preparation and Economic Analysis of High-current-density Electrocatalysts for Alkaline Water Electrolysis[J]. Journal of Inorganic Materials, 2025, 40(12): 1405-1413.

Figures/Tables 16

Fig. 1 Microstructure of NiMoOP/NF (a-c) SEM images; (d-f) TEM images

Fig. 2 XRD patterns and XPS spectra of NiMoO4·xH2O/NF and NiMoOP/NF (a) XRD patterns; (b) Full XPS spectra; (c) Ni2p XPS spectra; (d) Mo3d XPS spectra; (e) O1s XPS spectra; (f) P2p XPS spectrum

Fig. 3 Electrochemical performance tests of NiMoOP/NF and comparison with other catalytic materials (a) LSV curves; (b) Overpotentials; (c) Tafel plots; (d) Comparison of overpotentials for Ni-based catalysts; (e) I-t curve at -0.9 V (vs. RHE) without IR correction; (f) LSV curves of the catalyst before and after the 1100 h stability test; (g) Comparison of catalysts durability. Colorful figures are available on website

Fig. 4 OER performance of NiMoOP/NF and other catalytic materials (a) LSV curves; (b) Overpotentials; (c) Tafel plots; (d) Comparison of overpotentials with different catalysts. Colorful figures are available on website

Fig. 5 Performance and STH calculation of overall water splitting for NiMoOP/NF (a) LSV curves for overall water splitting; (b) Comparison of cell voltages at 10 and 100 mA·cm-2; (c) J-V curves of crystalline silicon heterojunction solar cells and polarization curves of the overall water splitting system; (d) Overall water splitting performance test under industrial simulation conditions (30% (in mass) KOH, 60 ℃). Colorful figures are available on website

Fig. 6 LCOH in (a) non-storage and (b) storage modes

Fig. S1 S1 Microstructures of NiMoO4·xH2O/NF (a-c) SEM images; (d, e) TEM images; (f) Selected area HRTEM image

Fig. S2 Tafel plots of four catalytic materials for eliminating diffusion effects at high current densities

Fig. S3 (a) Nyquist plots of NiMoO4·xH2O/NF, NiMoOP/NF, and NF; (b, c) Bode plots of (b) NiMoO4·xH2O/NF and (c) NiMoOP/NF

Fig. S4 I-t curve of the supplementary electrolyte

Fig. S5 Electrochemical activation phenomenon and ion dissolution data of NiMoOP/NF (a) I-t curve during initial 5 h of reaction; (b) Ni and Mo elemental concentrations in the electrolyte at initial stage of the reaction; (c) Ni and (d) Mo elemental concentrations in the electrolyte after 600 and 1100 h reaction

Fig. S6 XPS spectra of NiMoOP/NF before and after 50 h of HER (a) Ni2p; (b) Mo3d; (c) O1s; (d) P2p

Fig. S7 CV curves and double-layer capacitance of NiMoOP/NF before and after 10 h of HER (a) Initial NiMoOP/NF; (b) NiMoOP/NF after 10 h of HER; (c) Double-layer capacitance before and after HER

Fig. S8 SEM images of NiMoOP/NF at various magnifications after 1100 h of HER durability testing

Fig. S9 Faraday efficiency testing of NiMoOP/NF (a) Faraday efficiency results; (b) Photo of liquid level before reaction; (c) Photo of liquid level after reaction

Fig. S10 Operation of each system module at (a, d) 4.19, (b, e) 4.5 and (c, f) 5 kWh·Nm-3 under (a-c) non-storage and (d-f) storage modes

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