RESUMEN
Electron spin polarization is identified as a promising avenue for enhancing the oxygen evolution reaction (OER), which is the bottleneck that limits the energy efficiency of water-splitting. Here, we report that both ferrimagnetic (f-Fe3O4) and superparamagnetic iron oxide (s-Fe3O4) catalysts can exhibit external magnetic field (Hext)-induced OER enhancement, and the activity is proportional to their intrinsic magnetic moment. Additionally, the chirality-induced spin selectivity (CISS) effect was utilized in synergy with Hext to get a maximum enhancement of up to 89% improvement in current density (at 1.8 V vs RHE) with a low onset potential of 270 mV in s-Fe3O4 catalysts. Spin polarization and the resultant spin selectivity suppress the production of H2O2 and promote the formation of ground state triplet O2 during the OER. Furthermore, the design of chiral s-Fe3O4 with synergistic spin potential effect demonstrates a high spin polarization of â¼42%, as measured using conductive atomic force microscopy (c-AFM).
RESUMEN
Tailoring the curvature-directed lattice strain in GNRs along with optimal surface anchoring of molybdenum disulfide (MoS2) quantum dots (QDs) can lead to a unique heterostructure with Pt-like HER activity (onset potential -60 mV). The curvature-induced electronic charge redistribution at the curved region in the graphene nanoribbons allows a facile GNR-MoS2 interfacial charge transfer in the heterostructure, making the interfacial sulfur (S) more active towards the HER. The density functional theory (DFT) calculations confirmed electronically activated interfacial S-based catalytic centers in the curved GNR-based heterostructure leading to Pt-like HER activity.
RESUMEN
The enhanced safety, superior energy, and power density of rechargeable metal-air batteries make them ideal energy storage systems for application in energy grids and electric vehicles. However, the absence of a cost-effective and stable bifunctional catalyst that can replace expensive platinum (Pt)-based catalyst to promote oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode hinders their broader adaptation. Here, it is demonstrated that Tin (Sn) doped ß-gallium oxide (ß-Ga2 O3 ) in the bulk form can efficiently catalyze ORR and OER and, hence, be applied as the cathode in Zn-air batteries. The Sn-doped ß-Ga2 O3 sample with 15% Sn (Snx =0.15 -Ga2 O3 ) displayed exceptional catalytic activity for a bulk, non-noble metal-based catalyst. When used as a cathode, the excellent electrocatalytic bifunctional activity of Snx =0.15 -Ga2 O3 leads to a prototype Zn-air battery with a high-power density of 138 mW cm-2 and improved cycling stability compared to devices with benchmark Pt-based cathode. The combined experimental and theoretical exploration revealed that the Lewis acid sites in ß-Ga2 O3 aid in regulating the electron density distribution on the Sn-doped sites, optimize the adsorption energies of reaction intermediates, and facilitate the formation of critical reaction intermediate (O*), leading to enhanced electrocatalytic activity.
RESUMEN
The objective of the current study is to evaluate both the positive and negative effects of manganese-doped graphene quantum dots (GQD-Mn) on Capsicum annuum L. grown under salt stress. GQD-Mn was synthesized, characterized, and foliar-applied (250 mg/L, 120 mg/L, 60 mg/L) to C. annuum L. before and after the flowering stage, during which 100 mM of NaCl solution was introduced into the soil as salt stress. Controls were designed as absolute control (no nanomaterials or salt) and negative control (no nanomaterials only salt). Herein, we report that GQD-Mn offset the reduction of fruit production in salt-stressed C. annuum L. by around 40 %. However, based on a comprehensive analysis of normal alkanes (n-alkane) using gas chromatography-mass spectrometry (GC-MS), we also observed that the leaf epicuticular wax profile was disturbed by GQD-Mn, as the concentration of long-chain n-alkanes was increased. Meanwhile, the content of magnesium (Mg) and zinc (Zn) indicated a potential promoted photosynthesis activity in C. annuum L leaves. We hypothesize that the optical properties of GQD-Mn allow leaves to utilize light more efficiently, thus improving photosynthetic activities in plants to acclimate salt stress. But the increased light usage also induced heat stress on the leaf surfaces, which caused n-alkanes changes. Our results provided a unique perspective on nano-plant interaction that value both beneficial and toxic effects of nanomaterials, especially when evaluating the safety of nano-enabled agriculture in areas facing harsh environmental conditions such as salinity.
