RESUMEN
Finding clean, sustainable, and environmentally friendly technologies is especially crucial in addressing both energy and environmental challenges. To accelerate the oxygen evolution reaction (OER) and to overcome the obstacle of high energy consumption, exploring high-performance electrocatalysts is imperative to maximize the practical applicability of water splitting. Developing electrocatalyst through strategic surface modifications represents a significant approach for the construction of active catalytic centers. In the present work, we successfully synthesized selenium-incorporated hollow NiCo2O4/NiO heterostructured nanocages as electrocatalysts for the OER by precisely controlling the structure and composition of the material. The findings demonstrated that the surface-reconstructed hollow 5 wt% Se-NiCo2O4/NiO heterostructured nanocages resulted in an increased number of active sites through interfacial engineering. Benefiting from the structural control, mass transport was further expedited and due to increased conductivity, accelerated the charge transfer processes within the system. The electrocatalyst exhibited remarkable activity for the OER and displayed a low overpotential (η = 288 mV) at a current density (j) of 10 mA cm-2, small Tafel slope (66.7 mV dec-1) and better stability. This work offers a viable and adaptable method for fabricating a range of functional coordinated MOF compounds that are capable of utilization across diverse energy applications, including storage, conversion and environmental purposes.
RESUMEN
Clean water and sanitation are two of the most important challenges worldwide and the main source for freshwater is groundwater. Nowadays, water is polluted by human activities. Concern about the presence of nitrates (NO3-) in groundwater is increasing day-by-day due to the intensive use of fertilizers and other anthropogenic sources, such as sewage or industrial wastewater discharge. Thus, the main solution available is to remove NO3- from groundwater and transfer it back to a usable nitrogen source. Electrochemical reduction of NO3- to ammonia (NH3) under ambient conditions is a highly desirable method and it needs an efficient electrocatalyst. In this work, we synthesized a composite of amorphous boron with graphene oxide (B@GO) as an efficient catalyst for the nitrate reduction reaction. XRD and TEM analysis revealed an amorphous boron decoration on the graphene oxide sheet, and XPS confirmed that no bonding between boron and carbon occurs. In B@GO, a stronger defect carbon peak was observed than in GO and there was a random distribution of boron particles on the surface of the graphene nanosheets. Amorphous boron exhibits a higher bond energy, more reactivity, and chemical activity toward nitrate ions, which could be due to the lone pair present in the B atoms and could also be due to the edge oxidized B atoms. B@GO has a high number of active sites exposed leading to excellent nitrate reduction performance with a faradaic efficiency of 61.88% and good ammonia formation rate of 40006 µg h-1 mcat-1 at -0.8 V versus reversible hydrogen electrode.
