This review presents a comparative discussion with respect to the effects strongly correlated with electrochemical CO₂ reduction, including intrinsic effects of materials, structure-induced effects, electrolyte effects, and environment effects.

Sr _1.95 Ce _0.05 Fe _1.3 Ni _0.2 Mo _0.5 O _{6− δ} with optimal Ce doping allowed in situ co-exsolving CeO ₂ phase and NiFe nanoalloys on the surface, which achieved a high current density of 1.57 A cm ⁻² at 1.5 V and 850 °C with a CO faradaic efficiency of over 96%.

Numerous strategies have been devised to optimize the intrinsic activity of perovskite oxides for the oxygen evolution reaction (OER). However, conventional synthetic routes typically yield limited numbers of active sites and low mass activities. More critically, the sluggish mass transfer poses a huge challenge, particularly under high polarization conditions, which impedes the overall reaction kinetics. Herein, lacunaris La_0.5Pr_0.25Ba_0.25Co_0.8Ni_0.2O_3−δ nanotubes (LPBCN-NTs) were prepared via electrospinning and post-annealing, which exhibited a small overpotential of 358.8 mV at 10 mA cm⁻² and a lower Tafel slope of 71.46 mV dec⁻¹, superior to the values for the same stoichiometric LPBCN nanoparticles and solid nanofibers, state-of-the-art counterparts and commercial IrO₂. Density functional theory calculations revealed that the surface oxygen vacancies in LPBCN-NTs significantly lowered the OH⁻ adsorption energy, while finite element analysis indicated that the precisely constructed lacunaris NT structure enriched the OH⁻ concentration at its inner surface by an order of magnitude, both of which collectively resulted in accelerated OER kinetics. This study clarifies the underlying mechanism of how the lacunaris nanotubular architecture and the surface oxygen vacancies of perovskite oxides affect heterocatalysis, which undoubtedly paves the way to handling the long-standing issues of sluggish mass transfer rates and poor intrinsic catalytic activity.

The preparation of high-purity sulfur and pyrrhotite by pyrolysis holds great potential to realize the high-value utilization of pyrite concentrate (FeS₂), i.e., a by-product during the flotation of sulfide ore. In this study, the pyrrhotite obtained from the pyrolysis of pyrite concentrate was taken as the study object, and the effects of acid types, initial acidity, leaching time, leaching temperature, oxygen pressure, and liquid-to-solid ratio on the leaching behavior of pyrrhotite under oxygen pressure, were explored. The results show that elemental sulfur and hematite-based iron residue can be obtained by oxygen pressure leaching of pyrrhotite. It is found that the optimal experimental conditions for pyrrhotite oxygen pressure leaching are hydrochloric acid with 0.8 mol/L of initial acidity, 5 h of leaching time, 0.8 MPa of oxygen partial pressure, and 9:1 of liquid to solid ratio at 150 °C; moreover, the yield of sulfur reached 88.37%. Under optimal conditions, the leaching ratios of Fe, Pb, and Zn were 19.8%, 92.25%, and 99.11%, respectively. The sieved leaching residue was roasted at a low temperature of 500 °C, where the grade of Fe in the obtained hematite iron powder was 61.46%, and the grades of Pb, Zn, and S were 0.082%, 0.024%, and 0.1%. Clearly, the results meet well with the standard of the first grade of pyrite cinder, and this process realizes the comprehensive recovery of Fe and S resources in pyrolysis slag, which provides a superb technical route for the high-value utilization of pyrite concentrate.