A Breakthrough in Ammonia Decomposition for Hydrogen Production at Hunan University: Cobalt-Based Catalyst Spin-State Engineering Enhances Hydrogen Production Efficiency

A Hunan University team published their findings in the journal Energy Fuels (DOI: ), proposing that spin-state engineering of cobalt-based catalysts can optimize ammonia decomposition for hydrogen production, offering a new paradigm for catalyst design and the upgrading of ammonia-to-hydrogen technology. The study was conducted by Gong Xingchen (School of Chemistry and Chemical Engineering, Hunan University; research focus: ammonia decomposition for hydrogen production) and co-workers.

Core Research Concept and Technical Breakthrough

Ammonia decomposition is a key route for hydrogen production; the performance of transition-metal catalysts directly determines hydrogen yield, and tuning the metal spin state has become a decisive lever for tailoring catalytic behavior. Until now, this approach had not been demonstrated in ammonia decomposition. This work is the first to achieve controllable modulation of cobalt spin states during ammonia decomposition.

The team synthesized a series of Co/Li₂O–La₂O₃ composite catalysts via in-situ reduction sol–gel method and systematically investigated how lanthanum (La) content influences cobalt spin states:

Structural and magnetic characterizations revealed that as the La content increases, cobalt spin states can be controllably switched from “high spin” to “low spin”;

among the samples, the Co/Li₂O–La₂O₃-2 catalyst exhibited a unique “intermediate spin state,” a central finding corroborated by both experimental tests and density-functional theory (DFT) calculations.

Performance Advantages of the Intermediate-Spin Catalyst

The intermediate spin state of this catalyst provides an optimal match for the ammonia decomposition process, effectively resolving the traditional trade-off between “ammonia adsorption strength” and “reaction energy-barrier balance”:

Moderate NH₃ adsorption strength: it avoids the overly strong adsorption seen in high-spin states that hinders intermediate desorption, as well as the overly weak adsorption in low-spin states that fails to capture reactants efficiently;

Balanced energy barriers: it simultaneously improves H₂ dissociation efficiency and N₂ desorption rate, leading to a synergistic enhancement of both key steps and a marked increase in overall ammonia-to-hydrogen conversion efficiency.

Research Value and Significance

Academically, this study is the first to validate the effectiveness of “spin-state engineering” in optimizing ammonia-decomposition catalysts, moving beyond the conventional reliance on compositional or morphological tuning and opening a new research direction of “electronic-state regulation” in heterogeneous catalysis. Practically, cobalt-based catalysts optimized via spin-state engineering are expected to lower the reaction conditions (temperature, pressure) and costs of ammonia decomposition, thereby providing technical support for the large-scale use of ammonia as a “hydrogen carrier” in distributed hydrogen production and hydrogen storage/transport systems.