Boosting electrochemical nitrogen reduction to ammonia with high efficiency using a LiNb3O8 electrocatalyst in neutral media.

The nitrogen reduction reaction (NRR) has great potential as a method to replace the industrial Haber-Bosch process for ammonia synthesis. Nevertheless, the efficiency of the NRR is mainly dependent on the rational design of highly efficient and active electrocatalysts on account of the high energy of N2 and HER as a competitive reaction. Herein, a simple solid-phase synthesis method is adopted to design and synthesize a LiNb3O8 (LNO) electrocatalyst, which proves that the synergistic effect of electron-rich Nb and Li elements can effectively improve the NRR activity of commercial Nb2O5 and Li2CO3. The resultant LNO electrocatalyst presents an ammonia yield rate of 7.85 µg h-1 mgcat.-1 with a faradaic efficiency of 82.83% at -0.4 V vs. RHE under ambient conditions, which are much higher than those of commercial Nb2O5 (1.67 µg h-1 mgcat.-1, 13.51%) and Li2CO3 (1.93 µg h-1 mgcat.-1, 8.41%). Detailed characterizations demonstrate that the obtained LNO electrocatalyst has a larger specific surface area of electrochemical activity and more active sites to promote the activity of the NRR. Moreover, the synergistic effect of Li and Nb elements greatly improves the hydrophobicity of the material, which is more conducive to the occurrence of the NRR. This work highlights the enormous potential of the LNO electrocatalyst with a hydrophobic surface and easy activation of NN for highly efficient ammonia synthesis under ambient conditions.

Advances in the use of microalgal-bacterial consortia for wastewater treatment: Community structures, interactions, economic resource reclamation, and study techniques.

The rise in living standards has generated a demand for higher aquatic environmental quality. The microalgal community and the surrounding organic molecules, environmental factors, and microorganisms, such as bacteria, are together defined as the phycosphere. The bacteria in the phycosphere can form consortia with microalgae through various forms of interaction. The study of the species in these consortia and their relative proportions is of great significance in determining the species and strains of stable algae that can be used in sewage treatment. This article summarizes the following topics: the interactions between microalgae and bacteria that are required to establish consortia; how symbiosis between algae and bacteria is established; microalgal competition with bacteria through inhibition and anti-inhibition strategies; the influence of environmental factors on microalgal-bacterial aggregates, such as illumination conditions, pH, dissolved oxygen, temperature, and nutrient levels; the application of algal-bacterial aggregates to enhance biomass production and nutrient reuse; and techniques for studying the community structure and interactions of algal-bacterial consortia, such as microscopy, flow cytometry, and omics. PRACTITIONER POINTS: Community structures in microalgal-bacterial consortia in wastewater treatment. Interactions between algae and bacteria in wastewater treatment. Effects of ecological factors on the algal-bacterial community in wastewater treatment. Economically recycling resources from algal-bacterial consortia based on wastewater. Technologies for studying microalgal-bacterial consortia in wastewater treatment.