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The oxygen evolution reaction (OER) process involves the magnetic reversal of oxygen-containing intermediates, and the influence of defect structures on the magnetic behavior of catalysts might play a crucial role in this process. There is scarce research on the intrinsic relationship among defects, magnetism and catalysis. Herein, cation vacancy β -Ni(OH) 2 nanosheets were successfully prepared through alkaline selective etching. To further analyze their spin-magnetic behavior, we found that the presence of defects caused the transformation of Ni(OH) 2 from antiferromagnetic to ferromagnetic. Furthermore, to further elucidate their intrinsic spin-magnetic effects, it was observed that the initially antiferromagnetic β -Ni(OH) 2 exhibited almost no spin-magnetic response upon the introduction of a magnetic field, with the overpotential almost unchanged. Conversely, introducing defect structures showed a noticeable spin-magnetic effect, reducing the overpotential by 20 mV at 20 mA cm−2. The combination of defects and magnetic fields provides new principles for developing high-performance catalysts and understanding catalytic mechanisms at the spin-electronic level. • Ni 1-x Vac x (OH) 2 was prepared to investigate the spin-magnetic behavior of defect. • The defects of Ni(OH) 2 led to transformation from antiferromagnetic to ferromagnetic. • The spin-magnetic effect can reduce the overpotential by 20 mV at 20 mA cm−2. [ABSTRACT FROM AUTHOR]

Achieving improved energy efficiency, a green economy and degradation of environmental pollutants are important challenges to achieving sustainable development strategies. Herein, we have designed and synthesized a series of LaFe 1-x O 3 (LaFeO 3 , LaFe 0.95 O 3 , and LaFe 0.9 O 3) crystals with Fe vacancies for photo-assisted electrocatalysis (PAEC). These catalysts are used for both the anodic and cathodic reactions, where the anode efficiently removes persistent organic pollutants such as methylene blue (MB), and the cathode converts water into hydrogen gas. We observed that the presence of Fe vacancies leads to rearranging the electronic structure on the surface, enhancing the photo-assisted electrocatalytic activity. The rate constant for the photo-assisted electrocatalytic LaFe 0.90 O 3 was measured to be 0.996 min−1, which is 2.37 times and 2.74 times higher than that of the electrocatalytic (0.420 min−1) and photocatalytic (0.363 min−1) processes, respectively. The hydrogen production efficiency reached 1.42 μmol min−1. This study provides the first evidence of the photo-assisted electrocatalytic mechanism and potential applications of LaFeO 3 -based catalysts in enhancing the electro-oxidation of pollutants. It offers additional insights for the rational design and construction of more efficient PAEC catalysts for effective wastewater purification and energy recovery. [Display omitted] • The photo-assisted electrocatalysis for LaFe 1-x O 3 has been demonstrated. • The LaFe 0.90 O 3 owned outstanding electrocatalytic and photocatalytic performance. • The presence of Fe vacancies can enhance photo-assisted electrocatalytic activity. [ABSTRACT FROM AUTHOR]