James Robert Jennings

Developing cost-effective, methanol-tolerant oxygen reduction reaction (ORR) electrocatalysts is critical for alkaline fuel cells and metal–air batteries. This study presents the synthesis of CoTiO3 and Co1–xNixTiO3 (x = 0.1 and 0.2) ilmenite oxides via a sol–gel method and thoroughly examines the influence of Ni substitution in CoTiO3 on its ORR performance. XRD, FTIR, Raman, and XPS analyses confirmed the formation of the ilmenite CoTiO3 framework, successful Ni incorporation, and Ni-induced modulation of the metal–oxygen environment. TEM and FE-SEM analyses revealed nearly spherical nanoparticles, while EDAX verified the expected constituent elements. BET analysis showed that Co0.9Ni0.1TiO3 possessed the highest surface area and pore volume, supporting improved active-site accessibility. Electrocatalytic ORR studies in O2-saturated 1 M KOH demonstrated that Co0.9Ni0.1TiO3 exhibited the best ORR activity among the investigated oxides, with higher cathodic current density, lower charge-transfer resistance, lower Tafel slope, higher exchange current density, increased ECSA, and an apparent near-four-electron ORR pathway, comparable to Pt/C. Co0.9Ni0.1TiO3 also showed excellent methanol tolerance, retaining 84.36% current after 10,000 s in 1 M KOH containing 1 M methanol and 89.98% after 20,000 s in methanol-free 1 M KOH, highlighting its potential as a cost-effective ORR electrocatalyst.

The dynamics of calcium carbonate structures in marine organisms (skeletons and shells) has become increasingly important due to heightened interest in marine environmental acidification. Research into molluscan shell corrosion and calcification in response to acidification is typically carried out in laboratory-controlled settings, which often overlooks the intricate interactions found in natural environments. Mollusks inhabiting intertidal zones are especially susceptible to intense shell weathering caused by tidal cycles of heating, cooling, wetting, and drying, exacerbated by solar radiation during periods of air exposure. We investigated the effect of sun exposure (solar radiative heating) on both outer shell corrosion and inner shell compensatory calcification in the tropical oyster, Saccostrea scyphophilla. Shell properties were compared between oysters from neighboring populations in sun-exposed and shaded habitats. Habitat temperatures were measured using iButtons, and right shell valve corrosion was quantified. Compensatory calcification was assessed through measurements of shell thickness, shell density, shell compression strength, and mineralogical properties. Our results revealed that oysters in the sun that experience global irradiance, higher temperature peaks and broader daily temperature ranges (averaging an increase of 10 °C) show considerably greater outer shell surface corrosion (87%) compared to shaded oysters (31%) that experience only diffuse irradiance. Sun-exposed shells also become thickened in the midsection and around the adductor muscle, and they are slightly stronger, indicating compensation for the outer shell loss. These findings highlight the need for caution when interpreting molluscan shell dynamics based on laboratory marine acidification protocols that fail to account for the many natural environmental factors influencing shell formation and dissolution.

Methanol crossover severely limits the performance of direct methanol fuel cells (DMFCs) by introducing methanol to the cathode compartment, where it competes with the oxygen reduction reaction (ORR) and poisons platinum-based ORR electrocatalysts, making it essential to develop methanol-tolerant ORR electrocatalysts. Here, Ni doping is explored as a means of improving the electrocatalytic activity and methanol tolerance of LaCo_1–x Ni _x O₃ (x = 0, 0.1, 0.15, and 0.2) perovskite oxide electrocatalysts synthesized using a simple sol–gel method. X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray (EDAX) analysis confirm the formation of LaCoO₃ and successful Ni doping at the Co site. Field-emission scanning electron microscopy (FE-SEM) analysis reveals that the particle size of the synthesized nanoparticles slightly increases upon Ni doping. Although a corresponding decrease in Brunauer–Emmett–Teller (BET) surface area with increasing Ni doping is also found, LaCo_0.8Ni_0.2O₃ possesses the highest pore volume and pore radius among all the synthesized perovskite oxides. This optimized composition exhibits superior ORR catalytic activity (0.724 and 0.678 V vs reversible hydrogen electrode (RHE) at current densities of −0.1 and −0.3 mA cm^–2, respectively) comparable to Pt/C (0.758 and 0.709 V vs RHE) derived from the linear sweep voltammetry (LSV) study performed at 1600 rpm. In the presence of methanol, all the synthesized perovskite oxides experienced a small negative potential shift (0 to 14 mV) during ORR, suggesting these materials can be used as methanol-tolerant ORR electrocatalysts in DMFCs.

Tailoring LaBO₃ (B = Mn, Fe, Co, and Ni) perovskite oxides for methanol-tolerant electrocatalysts for oxygen reduction reaction.

The effect of different percentages of CdS on the structural, optical, and morphological properties of Cu_0.5Mg_2.5SnS₄ (CMTS) synthesized using a microwave method for photocatalytic degradation of brilliant green dye.