© 2020, The Author(s), under exclusive licence to Springer Nature Limited. The use of nitrogen fertilizers has been estimated to have supported 27% of the world's population over the past century. Urea (CO(NH2)2) is conventionally synthesized through two consecutive industrial processes, N2 + H2 → NH3 followed by NH3 + CO2 → urea. Both reactions operate under harsh conditions and consume more than 2% of the world's energy. Urea synthesis consumes approximately 80% of the NH3 produced globally. Here we directly coupled N2 and CO2 in H2O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO2 nanosheets. This coupling reaction occurs through the formation of C-N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g-1 h-1 and corresponding Faradic efficiency of 8.92% were measured at-0.4 V versus reversible hydrogen electrode.

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The nitrogenous nucleophile electrooxidation reaction (NOR) playsavital role in the degradation and transformation of available nitrogen. Focusing on the NOR mediated by the b-Ni(OH) 2 electrode,w ed ecipher the transformation mechanism of the nitrogenous nucleophile.F or the two-step NOR, proton-coupled electron transfer (PCET) is the bridge between electrocatalytic dehydrogenation from b-Ni(OH) 2 to b-Ni(OH)O,a nd the spontaneous nucleophile dehydrogenative oxidation reaction. This theory can give ag ood explanation for hydrazine and primary amine oxidation reactions,but is insufficient for the urea oxidation reaction (UOR). Through operando tracing of bond rupture and formation processes during the UOR, as well as theoretical calculations,wepropose apossible UOR mechanism whereby intramolecular coupling of the N À Nb ond, accompanied by PCET,hydration and rearrangement processes,results in high performance and ca. 100 %N 2 selectivity.T hese discoveries clarify the evolution of nitrogenous molecules during the NOR, and they elucidate fundamental aspects of electrocatalysis involving nitrogen-containing species.

A unique aerophilic-hydrophilic heterostructure composed of Au nanoparticles highly dispersed in a poly(tetrafluoroethylene) porous framework is fabricated on a Si-based photocathode for N 2 -to-NH 3 fixation. The amphipathic nature of the heterostructure is considered to be the origin of the enhanced nitrogen reduction reaction with efficient conversion efficiency and high production rate.

G-quadruplex containing peroxidase DNAzyme is a complex of hemin and a single-stranded guanine-rich DNA (hemin-binding DNA aptamer), which is used as an attractive catalytic label for biosensing recently. Therein, the hemin-binding DNA aptamer contains four GGG repeats and can fold into a G-quadruplex structure. In this paper, we have developed a new split mode to divide the hemin-binding DNA aptamer into two parts: one possesses three GGG repeats, and another part possesses one GGG repeat, namely, the 3:1 split mode. The combination of G-quadruplex and hemin binding could be used as a sensitive probe for the identification of single nucleotide polymorphisms by giving a color signal, visible to the naked eye at room temperature. The G-quadruplex containing peroxidase DNAzyme utilizes the 3:1 split mode and can be directly used for the identification of SNPs with a detection limit in the nM range when the matching length of the probe is short enough. When the matching length of the probe is relatively long, another method adding competition sequences to the probe could also operate effectively for the identification of SNPs. The results also suggested that we could detect the signal when the mutation sample was only 5% in the total target DNA with a competition strategy.