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Patterning of colloidal particles with chemically or topographically distinct surface domains (patches) has attracted intense research interest. Surface-patterned particles act as colloidal analogues of atoms and molecules, serve as model systems in studies of phase transitions in liquid systems, behave as 'colloidal surfactants' and function as templates for the synthesis of hybrid particles. The generation of micrometre- and submicrometre-sized patchy colloids is now efficient, but surface patterning of inorganic colloidal nanoparticles with dimensions of the order of tens of nanometres is uncommon. Such nanoparticles exhibit size- and shape-dependent optical, electronic and magnetic properties, and their assemblies show new collective properties. At present, nanoparticle patterning is limited to the generation of two-patch nanoparticles, and nanoparticles with surface ripples or a 'raspberry' surface morphology. Here we demonstrate nanoparticle surface patterning, which utilizes thermodynamically driven segregation of polymer ligands from a uniform polymer brush into surface-pinned micelles following a change in solvent quality. Patch formation is reversible but can be permanently preserved using a photocrosslinking step. The methodology offers the ability to control the dimensions of patches, their spatial distribution and the number of patches per nanoparticle, in agreement with a theoretical model. The versatility of the strategy is demonstrated by patterning nanoparticles with different dimensions, shapes and compositions, tethered with various types of polymers and subjected to different external stimuli. These patchy nanocolloids have potential applications in fundamental research, the self-assembly of nanomaterials, diagnostics, sensing and colloidal stabilization.

The electrocatalyzed ammonia oxidation reaction (AOR) is a potential pathway toward waste ammonia remediation, energy generation, and the synthesis of value‐added products. To date, mechanistic studies have focused on elucidating the progress of AOR on Pt‐based catalysts with an established pathway for N2$\mathrm{N_2}$ only. In this work, density functional theory was applied to determine the lowest energy intermediates toward nitrogen gas, nitrite, and nitrate formation on β$\beta$‐Ni(OH)2$\mathrm{Ni(OH)_2}$, a promising electrocatalyst material for AOR. It was found that dinitrogen formation progresses via NH‐NH coupling, whereas nitrite and nitrate formation occurs via deprotonation of ammonia to form adsorbed N and subsequent hydroxylation to form oxygenated intermediates. This work is the first to report a mechanism for nitrite and nitrate formation and will also serve as a benchmark for future studies on Ni‐based materials. [ABSTRACT FROM AUTHOR]

We discuss the environmental and energetic benefits of coupling nitrogenous waste treatment with the electrochemical conversion of CO2 to value-added products via direct reduction or electrocarboxylation. In particular, we demonstrate that co-electrolysis of urea or ammonia with CO2 requires significantly lower cell voltages than CO2 electrolyzers relying on the oxygen evolution reaction as an anodic process. [ABSTRACT FROM AUTHOR]

Abstract: Chemical and topographic surface patterning of inorganic polymer‐functionalized nanoparticles (NPs) and their self‐assembly in nanostructures with controllable architectures enable the design of new NP‐based materials. Capping of NPs with inorganic polymer ligands, such as metallopolymers, can lead to new synergetic properties of individual NPs or their assemblies, and enhance NP processing in functional materials. Here, for gold NPs functionalized with polyferrocenylsilane, two distinct triggers are used to induce attraction between the polymer ligands and achieve NP self‐assembly or topographic surface patterning of individual polymer‐capped NPs. Control of polymer–solvent interactions is achieved by either changing the solvent composition or by the electrooxidation of polyferrocenylsilane ligands. These results expand the range of polymer ligands used for NP assembly and patterning, and can be used to explore new self‐assembly modalities. The utilization of electrochemical polymer oxidation stimuli at easily accessible potentials broadens the range of stimuli leading to NP self‐assembly and patterning. [ABSTRACT FROM AUTHOR]

Herein, we report on the facile synthesis of nanocomposite consisting of TiO 2 and Au nanoparticles (NPs) via a tailored galvanic replacement reaction (GRR). The electrocatalytic activity of the synthesized TiO 2 /Au nanocomposites for CO 2 reduction was investigated in an aqueous solution using various electrochemical methods. Our results demonstrated that the TiO 2 /Au nanocomposites formed through the GRR process exhibited improved catalytic activities for CO 2 reduction, while generating more hydrocarbon molecules than the typical formation of CO in contrast to polycrystalline Au. GC analysis and NMR spectroscopy revealed that CO and CH 4 were the gas products, whereas HCOO - , CH 3 COO - , CH 3 OH, and CH 3 CH 2 OH were the liquid products from the CO 2 reduction at different cathodic potentials. This remarkable change was further studied using the density functional theory (DFT) calculations, showing that the TiO 2 /Au nanocomposites may increase the binding energy of the formed · CO intermediate and reduce the free energy compared to Au, thus favoring the downstream generation of multicarbon products. The TiO 2 /Au nanocomposites have high catalytic activity and excellent stability and are easy to fabricate, indicating that the developed catalyst has potential application in the electrochemical reduction of CO 2 to value-added products.