Nanjing Normal University

Electrocatalytic nitric oxide (NO) reduction reaction (NORR) is a promising and sustainable process that can simultaneously realize green ammonia (NH3) synthesis and hazardous NO removal. However, current NORR performances are far from practical needs due to the lack of efficient electrocatalysts. Engineering the lattice of metal-based nanomaterials via phase control has emerged as an effective strategy to modulate their intrinsic electrocatalytic properties. Herein, we realize boron (B)-insertion-induced phase regulation of rhodium (Rh) nanocrystals to obtain amorphous Rh4B nanoparticles (NPs) and hexagonal close-packed (hcp) RhB NPs through a facile wet-chemical method. A high Faradaic efficiency (92.1 ± 1.2%) and NH3 yield rate (629.5 ± 11.0 µmol h−1 cm−2) are achieved over hcp RhB NPs, far superior to those of most reported NORR nanocatalysts. In situ spectro-electrochemical analysis and density functional theory simulations reveal that the excellent electrocatalytic performances of hcp RhB NPs are attributed to the upshift of d-band center, enhanced NO adsorption/activation profile, and greatly reduced energy barrier of the rate-determining step. A demonstrative Zn–NO battery is assembled using hcp RhB NPs as the cathode and delivers a peak power density of 4.33 mW cm−2, realizing simultaneous NO removal, NH3 synthesis, and electricity output.

l-malic acid is a versatile compound having extensive applications across food, pharmaceutical, medical, and chemical industries while its production from microbial fermentation offers sustainable advantages including renewable feedstocks and environmental friendliness. However, a major challenge faced by microbial l-malic acid production is acid-induced pH drop during the fermentation process, requiring excessive neutralizers (e.g., CaCO₃) that increase costs and environmental burdens greatly. In this study, we firstly made an engineered Aspergillus nidulans strain as a production chassis through metabolic engineering by overexpression of fructose-6-phosphate kinase gene (pfkA) combined with deletion of pyruvate decarboxylase gene (pdcA) so that the titer of l-malic acid was increased by 20.3 %. Secondly, overexpression of glucose transporter gene (mstE) further boosted production to the highest reported shake-flask titer (44.3 g/L) for A. nidulans. Moreover, acid-tolerant isolates capable of growth at pH 2.8 has been successfully obtained by adaptive laboratory evolution in aforementioned engineered strains. They achieved 75 % neutralizer reduction (just adding 10 g/L CaCO₃) while maintaining original titers. Whole-genome sequencing comparison identified mutations in gene (ANIA_04699) encoding a protein with a topoisomerase II associated PAT I domain happened in acid-tolerance isolates. Functional validation via engineered point-mutants confirmed mutations of the gene (ANIA_04699) as a key acid-tolerance determinant, contributes a major role enabling CaCO3 reduction without titer loss. Meanwhile, phylogenetic studies showed there are about 71-75 % homology across selected Aspergillus spp. suggesting high conservation and broad applicability. Function prediction analysis based on previous verified PAT I domains imply that mutations of this topoisomerase II-Like protein might be tolerant to DNA damage induced by low pH environment. This work establishes A. nidulans as a platform for low-pH organic acid production and identifies topoisomerase II variants as new targeted candidates for acid tolerance engineering.

Efficient interfacial charge transfer and robust interface interactions are critical for superior charge carrier separation and advanced heterogeneous photocatalysts. Herein, a Schottky heterojunction has been designed by in situ growth of ZnIn₂S₄ (ZIS) nanosheets onto Co-doped FeP nanorods (Co_X-FePZ), building a dual electron transfer bridge (Fe-S/Zn-P). X-ray photoelectron spectroscopy, X-ray absorption fine structure, and density functional theory calculations prove that trace Co doping alters the chemical bonding structure and Fermi level (E_f) of FeP and ZIS, creating a Schottky heterojunction. The reversed internal electric field and dual electron transfer pathways provide driving force and transmission channels for electron flow. Schottky heterojunction prevents electron reflux and improves carrier separation efficiency, boosting photocatalytic hydrogen evolution. The optimized Co_2.5-FePZ achieves a remarkable H₂ production rate of 9.9 ± 0.1 mmol·g^-1·h^-1, approximately 12.4 times that of pure ZIS, with an apparent quantum yield (AQY) of 11 ± 1 % at 365 nm. This work delicately modulated the heterojunction interface and achieved the transition from an Ohmic heterojunction to a Schottky heterojunction, unveiling a novel strategy to optimize carrier migration pathways via trace element doping and covalent coupling.