Metal Deposition Research Articles

Molten Salt Electrodeposition: Review

Molten salt electrodeposition is the process of producing impressively dense deposits of refractory metals using the electrolysis of molten salts. However, predicting which electrochemical parameters and setup will best control different kinds of deposition (density, homogeneity, etc.) is an ongoing challenge, due to our limited understanding of the properties and mechanisms that drive molten salt electrodeposition. Because these advancements have been made rapidly and in different arenas, it is worth taking the time to stop and assess the progress of the field as a whole. These advancements have increasing relevance for the energy sector, the development of space materials and engineering applications. In this review, we assess four critical facets of this field: (1) how the current understanding of process variables enhances the electrodeposition of various molten salts and the quality of the resulting product; (2) how the electrochemical setup and the process parameters (e.g., cell reactions) are known to impact the electrodeposition of different metal coatings and refractory-metal coatings; (3) the benefits and drawbacks of non-aqueous molten salt electrodeposition, and (4) promising future avenues of research. The aim of this work is to enhance our understanding of the many procedures and variables that have been developed to date. The expectation is that this review will act as a stimulant, motivating scientists to delve further into the investigation of refractory-metal alloys by utilizing molten salt electrodeposition.

Placental Element Content Assessed via Synchrotron-Based X-ray Fluorescence Microscopy Identifies Low Molybdenum Concentrations in Foetal Growth Restriction, Postdate Delivery and Stillbirth.

Placental health and foetal development are dependent upon element homeostasis. Analytical techniques such as mass spectroscopy can provide quantitative data on element concentrations in placental tissue but do not show spatial distribution or co-localisation of elements that may affect placental function. The present study used synchrotron-based X-ray fluorescence microscopy to elucidate element content and distribution in healthy and pathological placental tissue. The X-ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron was used to image trace metal content of 19 placental sections from healthy term (n = 5, 37-39 weeks), foetal growth-restricted (n = 3, <32 weeks, birth weight <3rd centile), postdate (n = 7, >41 completed weeks), and stillbirth-complicated pregnancies (n = 4, 37-40 weeks). Samples were cryo-sectioned and freeze-dried. The concentration and distribution of fourteen elements were detected in all samples: arsenic, bromine, calcium, chlorine, copper, iron, molybdenum, phosphorous, potassium, rubidium, selenium, strontium, sulphur, and zinc. The elements zinc, calcium, phosphorous, and strontium were significantly increased in stillbirth placental tissue in comparison to healthy-term controls. Strontium, zinc, and calcium were found to co-localise in stillbirth tissue samples, and calcium and strontium concentrations were correlated in all placental groups. Molybdenum was significantly decreased in stillbirth, foetal growth-restricted, and postdate placental tissue in comparison to healthy-term samples (p < 0.0001). Synchrotron-based XFM reveals elemental distribution within biological samples such as the placenta, allowing for the co-localisation of metal deposits that may have a pathological role. Our pilot study further indicates low concentrations of placental molybdenum in pregnancies complicated by foetal growth restriction, postdate delivery, and stillbirth.

Enhanced photocatalysis-Fenton degradation of levofloxacin by Fe doped BiOCl microspheres with rich surface oxygen vacancies: The accelerated redox cycle of ≡Fe(III)/≡Fe(II)

The photocatalysis-Fenton process was considered as an effective water treatment method due to its superior efficiency and technical feasibility, but its application was limited by ≡Fe(III)/≡Fe(II). Herein, Fe doped BiOCl hierarchical microspheres with rich surface oxygen vacancies (Fe/BiOCl OVs) were synthesized to modulate the interface structure for efficient photocatalysis-Fenton degradation of levofloxacin (LEV). The systematic characterization analysis confirmed the existence of strong interfacial interactions, which facilitated the activation of H2O2 and the degradation of LEV. The synergism of metal deposition, OVs and surface plasmon resonance (SPR) effect of Bi contributed to the enhanced light absorption ability and suppressed carriers recombination. The LEV degradation efficiency reached 99.0% after 60-min photocatalysis-Fenton reaction. The interfacial charge transfer theory demonstrated that the presence of oxygen vacancies accelerated the redox cycle of ≡Fe(III)/≡Fe(II), which promoted the H2O2 activation to produce ·OH. The ·OH and e- played important roles during the photocatalysis-Fenton degradation of LEV, while ·O2–, 1O2 and h+ also contributed in LEV degradation. Based on density-functional theory (DFT) calculations and LC-MS analysis, four degradation pathways of LEV were proposed. The photocatalysis-Fenton degradation process of Fe/BiOCl OVs effectively reduced the toxicity of LEV, which ultimately mitigated the harmful effects of antibiotics on the environment.

Constructing Three-Dimensional Architectures to Design Advanced Copper-Based Current Collector Materials for Alkali Metal Batteries: From Nanoscale to Microscale.

Alkali metals (Li, Na, and K) are deemed as the ideal anode materials for next-generation high-energy-density batteries because of their high theoretical specific capacity and low redox potentials. However, alkali metal anodes (AMAs) still face some challenges hindering their further applications, including uncontrollable dendrite growth and unstable solid electrolyte interphase during cycling, resulting in low Coulombic efficiency and inferior cycling performance. In this regard, designing 3D current collectors as hosts for AMAs is one of the most effective ways to address the above-mentioned problems, because their sufficient space could accommodate AMAs' volume expansion, and their high specific surface area could lower the local current density, leading to the uniform deposition of alkali metals. Herein, we review recent progress on the application of 3D Cu-based current collectors in stable and dendrite-free AMAs. The most widely used modification methods of 3D Cu-based current collectors are summarized. Furthermore, the relationships among methods of modification, structure and composition, and the electrochemical properties of AMAs using Cu-based current collectors, are systematically discussed. Finally, the challenges and prospects for future study and applications of Cu-based current collectors in high-performance alkali metal batteries are proposed.

Advances in Nickel-Containing High-Entropy Alloys: From Fundamentals to Additive Manufacturing.

High-entropy alloys (HEAs) are recognized as a class of advanced materials with outstanding mechanical properties and corrosion resistance. Among these, nickel-based HEAs stand out for their impressive strength, ductility, and oxidation resistance. This review delves into the latest advancements in nickel-containing HEAs, covering their fundamental principles, alloy design strategies, and additive manufacturing techniques. We start by introducing HEAs and their unique properties, emphasizing the crucial role of nickel. This review examines the complex relationships between alloy composition, valence electron concentration (VEC), and the resulting crystal structures. This provides insights into design principles for achieving desired microstructures and mechanical properties. Additive manufacturing (AM) techniques like selective laser melting (SLM), electron beam melting (EBM), and laser metal deposition (LMD) are highlighted as powerful methods for fabricating intricate HEA components. The review addresses the challenges of AM processes, such as porosity, fusion defects, and anisotropic mechanical properties, and discusses strategies to mitigate these issues through process optimization and improved powder quality. The mechanical behavior of AM-processed nickel-based HEAs is thoroughly analyzed, focusing on compressive strength, hardness, and ductility. This review underscores the importance of microstructural features, including grain size, phase composition, and deformation mechanisms, in determining the mechanical performance of these alloys. Additionally, the influence of post-processing techniques, such as heat treatment and hot isostatic pressing (HIP) on enhancing mechanical properties is explored. This review also examines the oxidation behavior of nickel-containing HEAs, particularly the formation of protective oxide scales and their dependence on aluminum content. The interplay between composition, VEC, and oxidation resistance is discussed, offering valuable insights for designing corrosion resistant HEAs. Finally, this review outlines the potential applications of nickel-based HEAs in industries such as aerospace, automotive, and energy, and identifies future research directions to address challenges and fully realize the potential of these advanced materials.

Closed-Loop Control of Melt Pool Temperature during Laser Metal Deposition.

Laser metal deposition (LMD) is a technology for the production of near-net-shape components. It is necessary to control the manufacturing process to obtain good geometrical accuracy and metallurgical properties. In the present study, a closed-loop control method of melt pool temperature for the deposition of small Ti6Al4V blocks in open environment was proposed. Based on the developed melt pool temperature sensor and deposition height sensor, a closed-loop control system and proportional-integral (PI) controller were developed and tested. The results show that with a PI temperature controller, the melt pool temperature tends to the desired value and remains stable. Compared to the deposition block without the controller, a flatter surface and no oxidation phenomenon are obtained with the controller.

Theoretical-experimental study of Fe–ZrO2 and Co–ZrO2. Oxidative degradation of methyl orange azo dye

In recent years, advanced oxidation processes (AOPs) based on the generation of sulfate radicals (SO4●-) (SR-AOPs) have emerged as an innovative method for the decontamination of water and wastewater. In this study, Fe(II) and Co(II) catalysts supported on ZrO₂ were synthesized and employed as an activator for PMS and PS for the degradation of methyl orange. The general objective is to gain detailed insight into the interaction between oxidants and supported metal catalysts at the molecular level. Experimental results and density functional theory (DFT) calculations were employed to analyze the potential activation mechanism of the oxidants. The support was prepared via coprecipitation, and metal ion deposition was achieved through incipient wetness impregnation. The characterization of the catalysts was conducted through atomic absorption spectrometry, X-ray diffraction and Fourier-transform infrared spectroscopy. The findings indicated that PMS was the most efficient oxidant, with Co–ZrO2 emerging as the most effective catalyst (77% MO mineralization), compared to Fe–ZrO2, which exhibited a lower degree of mineralization (37.6%) under the specified experimental conditions. The use of PS as an oxidant resulted in low levels of degradation for both catalysts. The remarkable catalytic efficacy of the Co–ZrO₂/PMS system was elucidated through the application of density functional theory (DFT) calculations. These revealed that the adsorption energy of the oxidants on Co–ZrO₂ is lower than that on Fe–ZrO₂, which could facilitate the subsequent release of radicals to the reaction medium.

Microstructure and mechanical property improvement of concurrent wire-powder feeding laser melting deposition Ti-6Al-4V via TiC addition

Wire-feed laser metal deposition (LMD-W) offers a high deposition rate and low cost, making it an effective solution for reducing costs and enhancing efficiency in manufacturing large-scale titanium aerospace components. Currently, the material used for LMD-W is typically a single alloy wire, which limits the flexibility and functionality of manufacturing composite materials. This work employed a novel concurrent wire-powder feeding laser metal deposition (LMD-WP) process to manufacture TiC/Ti-6Al-4V composite. In the LMD-WP method, Ti-6Al-4V wire was fed laterally, while TiC particles were delivered coaxially. Only 1.0 wt% TiC particles were added to prevent excessive TiC, which could cause stress concentration and increase crack sensitivity. The microstructure and mechanical properties of Ti-6Al-4V alloy and TiC/Ti-6Al-4V composite were investigated. The results indicate that with coaxial TiC particle addition, the α-Ti in TiC/Ti-6Al-4V is noticeably refined. Additionally, in situ TiC acts as heterogeneous nucleation sites, restricting α-Ti growth and reducing its aspect ratio. Furthermore, TiC particles weakened the α-Ti texture in the (0001) and (11–20) directions. Moreover, adding TiC particles significantly enhanced tensile strength, with the yield strength reaching 950 MPa and the ultimate tensile strength reaching 1048 MPa. Compared to Ti-6Al-4V alloy fabricated by LMD-W, this represents an increase of 11.25% and 10.72%, respectively. The improvement in tensile properties is principally ascribed to grain boundary strengthening, Orowan strengthening and dislocation density strengthening. This work introduces an innovative approach and abundant data for the additive manufacturing of TiC/Ti-6Al-4V composite with high efficiency and low cost.

Pronounced declines in heavy metal burdens of Minnesotan mammals over the last century

Humans have drastically altered the ecology of heavy metals, which can have negative effects on animal development and neural functioning. Many species have shown the ability to adapt to anthropogenic increases in metal pollution, but such evolutionary responses will depend on the extent of metal variation over space and time. For terrestrial vertebrates, it is unclear how metal exposure has changed over time: some studies suggest metal content peaked with the enactment of policies controlling lead emissions, while other studies suggest metal levels peaked at least a century earlier. We used 162 specimens of four mammal species (a mouse, shrew, bat, and squirrel) to ask how metal content of the fur and skin has changed over a 90-year time period, and impacts on individual performance (body size and cranial capacity). Using ICP-MS, we show that for lead, cadmium, copper, and chromium, there were significant declines in metal content in mammal tissue over the 90-year time period, with lead levels five times lower now than in the early 1900s. Importantly, metal content began to drop well before the pollution regulation of the 1970s. Effects of time greatly outweighed any effects of an individual living near a human population center. Surprisingly, there were no effects of body metal content on body size, and only manganese was negatively related to relative cranial capacity. Taken together, these results suggest that present day populations of mammals are experiencing levels of heavy metal exposure that are less stressful than they were 100 years ago. In addition, temporal decreases in metal loads likely partly reflect global patterns of pollution decline that affect atmospheric metal deposition rather than local point sources of exposure.

Influence of Potential and the Presence of Boric Acid on Pt1-xCox Alloy Electrodeposition and Magnetic Properties

The effects of potential and the presence of B(OH)3 on Pt1-xCox alloy electrodeposition from aqueous chloride-based solutions on Ru substrates was investigated. Films deposited at potentials more reducing than −0.65 V vs SCE were hexagonal close packed and greater than 90% Co (mole basis), and films deposited at potentials more oxidizing than −0.65 V were face centered cubic and showed a monotonic decrease in cobalt content as the potential increased. The composition and structure-potential dependences were not strongly affected by the presence of B(OH)3. Structural change coincided with a distinct knee-like feature in the composition-potential relationship, along with a prominent narrow voltammetric peak associated with Co deposition, possibly related to nucleation and growth of the hcp phase. The presence of B(OH)3 produced a sharp minimum in both Coulombic efficiency and deposition rate at potentials near −0.65 V and almost entirely suppressed the voltammetric feature. This may be associated with a combination of B(OH)3-derived proton reduction and inhibition of metal deposition by adsorbed B(OH)3 or B(OH)3-derived species. The presence of B(OH)3 affected the magnetic behavior of films deposited at potentials more oxidizing than −0.55 V (i.e., those with compositions less than about 40% Co) only weakly, but resulted in generally smaller maximum magnetizations for films deposited at more reducing potentials, and notably a much lower magnetization for films deposited at −0.65 V.

The Metallurgy of Additive Manufacturing: Potentials and Challenges towards Industrialisation

Abstract The present paper discusses the potential and challenges of processing metallic materials using additive manufacturing. Particular focus is given to laser powder bed fusion (PBF-LB/M) and the use of traditional alloy powders such as Al alloys and Ni-based superalloys, as well as novel materials such as metal-matrix composites. The research includes the improvement of the processability of these alloys using PBF-LB/M and optimizing material properties such as strength, creep resistance, and thermal conductivity of printed parts for various applications. Another important aspect presented within this manuscript is the digital representation of advanced manufacturing systems to improve manufacturability and enable advanced quality control. Herein, the development of a digital twin through in-situ process monitoring for the direct energy deposition process of laser metal deposition is presented. In the last part, the future of materials development for additive manufacturing is discussed, focusing on applying material computational techniques. All demonstrated examples result from the successful cooperation between the Chair of Materials Engineering of Additive Manufacturing, TUM, and its industrial and research partners.

Effects of boron on microstructure, wear and corrosion properties of external magnetic field assisted laser metal deposition coatings

Coatings with different boron content were prepared by magnetic field-assisted Co-based laser metal deposition on 300 M ultra-high strength steel. The effects of boron content on the magnetic properties, mechanical properties, friction and wear properties, and corrosion resistance of the coating were investigated. The research results indicate that adding 6 wt% of boron to cobalt alloy in a 35 mT alternating magnetic field is beneficial for refining the microstructure, which can improve the mechanical properties of the coating. This research also discusses the effect of boron content on the wear and corrosion resistance of the coating. The results show that adding boron content enhances the magnetostrictive effect, and reduces the elastic modulus of the laser metal deposition coating while ensuring its hardness, thereby improving the wear and corrosion resistance of the laser metal deposition layer. The hardness of the coating can reach 1215 HV. The friction coefficient and corrosion current density of the coating are reduced by 26.9% and 60.2% respectively compared with the substrate. This work can help promote the application of laser metal deposition technology, reduce costs, and ensure performance.

Adaptive hybrid control for the formed morphology in powder-based laser metal deposition

Adaptive hybrid control for the formed morphology in powder-based laser metal deposition

Challenges and Progress in Anode‐Electrolyte Interfaces for Rechargeable Divalent Metal Batteries

AbstractDivalent metal batteries have attracted considerable attention in scientific exploration for sustainable energy storage solutions owing to the abundant reserves of magnesium (Mg) and calcium (Ca), the competitive low redox potentials of the Mg/Mg2+ (–2.37 V vs SHE) and Ca/Ca2+ (–2.87 V vs SHE) couples, as well as the high theoretical capacities of both metal anodes. However, the development of these batteries faces fundamental challenges stemming from the limited cycling stability and efficiency of Mg/Ca metal anodes. These issues primarily originate from the sluggish electrochemical redox kinetics of the divalent metals, particularly at the anode‐electrolyte interfaces. This comprehensive review provides an up‐to‐date overview of advancements in the field of the anode‐electrolyte interface for divalent metal batteries, covering aspects ranging from its formation, morphology, and composition to their influence on the reversible electrochemical deposition of divalent metals. Recent approaches aimed at enhancing the performance of metallic Mg and Ca anodes across various electrolytes are summarized and discussed, with the goal of providing insights for the development of new strategies in future research.

In situ three-dimensional reconstruction and gradient-induced design of ultrastable Zn metal anodes in Zn-Se batteries

Zinc-selenium batteries have high specific and volumetric capacities, but practical development faces key challenge in achieving stable zinc metal anodes, and avoiding zinc dendrite growth, hydrogen evolution reaction (HER) and corrosion. Here, a zinc foam substrate is employed to fabricate three-dimensional gradient electrodes Zn foam@Cu@CuSe2 (ZFCCS) with gradient change of zincophilicity and conductivity. Experimental observations and simulations collectively confirm that the three-dimensional structure and gradient design effectively homogenize interfacial ion flux and diminish local current density. This optimization of the zinc deposition path synergistically fosters high flux and deep deposition of zinc metal while simultaneously preventing dendrite growth. The results demonstrate that the developed ZFCCS electrode produces an excellent Coulombic efficiency of 99.5 % over 1000 plating/stripping cycles, and the corresponding symmetric cell provides an ultra-long dendrite-free cycle life of 800 h at 5 mA cm−2 and 2 mAh cm−2 with a low overpotential of 27.4 mV. In addition, the Zn-Se full cell based on the designed ZFCCS composite anode exerts superior stable cycle life (358.1 mAh g−1 at 2 A g−1 after 1000 cycles). Therefore, the gradient design strategy based on 3D electrodes will be a reference for high performance energy storage devices.

Bound metal deposition of stainless steel 316L: Effect of process variables on microstructural and mechanical behaviors

The influence of printing variables on microstructural and mechanical behaviors on the 316 L stainless steel (316 L SS), produced via an additive manufacturing process, named as bound metal deposition (BMD), was investigated in this study. The printing parameters varied were infill density, diameter of the nozzle, and thickness of layers, which dictate the mechanical properties, surface roughness, and crack morphology of the samples. Based on the experimental investigation, it was found that the tensile properties were increased when the nozzle diameter and infill density were higher. The highest obtained ultimate tensile strength (UTS) was 402 ± 17 MPa, where the sample was fabricated with the following parameters: 0.40 mm nozzle diameter, 25% infill density, and 0.10 mm layer. The influence of the nozzle diameter also impacted the surface roughness, where a worse surface finish was noticed for the larger nozzle diameter.

Electrical transport characteristics of atomic contact and nanogap dynamically formed by electromigration

The feature size of circuits was gradually reduced to a few nanometers, which is prone to lead to the failure of the metal circuit even upon a low bias voltage due to the electromigration. Therefore, it is essential to understand the electrical transport characteristics of a narrow metal wire shrunk to atomic scale due to electromigration. To this end, we report that the approach for metal deposition and the underneath substrate play a critical role in determining the electron transport behavior. It is observed that the conductance of the narrow metal wire fabricated on a SiO2 substrate first rises and then decreases during the electromigration process when the cross section of the metal wire is reduced to a few atoms. However, such a phenomenon is not observed for the metal wire fabricated on a polyimide substrate. Assisted by component analysis technology, it is revealed that the metal atoms can penetrate into the underneath substrate during the metal deposition process, and the metal atoms buried in the different substrates result in distinguished conductance behavior.

Long-life and high-power Sodium-Selenium Batteries realized by Vanadium single atom catalyzed cathodes and tailored carbonate-based electrolytes

The practical implementation of resources-abundant sodium-selenium batteries (SSBs) has been retarded by the low-capacity utilization and poor reversibility from the sluggish conversion kinetics of selenides, the notorious polyselenides shuttling effect and the dendritic deposition of sodium metal. This work presents a rational design of vanadium single atom catalyst on nitrogen-doped carbon sheets (V-N-C) as selenium host to address the instability of cathodes. Density function theory calculations reveal the superiority of V-N4 in V-N-C over other transition metal and nitrogen atoms in facilitating the adsorption-diffusion-conversion of polyselenides. Se@V-N-C cathodes deliver a high capacity utilization (603 mAh g−1 at 0.1 C, over 89 % of theoretical capacity), excellent reversibility (470 mAh g-1 at 0.1 C after 500 cycles), and remarkably high-power cyclability (260 mAh g−1 at 5 C over 1000 cycles). The prolong cycle life can also be originated from our tailored NaPF6 carbonate electrolyte with 1 wt% LiDFBOP additive. The new electrolyte is illustrated to generate inorganic-rich solid electrolyte interphase layers to protect sodium metal anodes from polyselenides corrosion and dendritic deposition at high rates. Fundamental findings in this work present a two-pronged approach to the prevailing challenges in the nascent metal-selenium battery chemistry.

Geochemistry of Middle Jurassic Coals from the Dananhu Mine, Xinjiang: Emphasis on Sediment Source and Control Factors of Critical Metals

In recent years, coal-type critical metal deposits have become a research hotspot in coal geology. As a major coal-accumulating basin in the Xinjiang area, the Turpan-Hami Basin contains abundant coal resources and has the potential to become a large coal-type critical metal deposit. However, previous studies on the enrichment characteristics of critical metal elements in coal are few and need further research. Based on SEM-EDS, XRF, and ICP-MS experiments, this study investigates the coal petrology, mineralogy, and geochemistry of the No. 22 coal of the Xishanyao Formation from the Dananhu Coal Mine, Xinjiang, to identify the sediment source, depositional environment, and controlling factors of the critical metal elements of the No. 22 coal. The results showed that the Dananhu coals are characterized by a low ash yield, low total sulfur content, high volatile yield, and high inertinite proportions. Quartz, kaolinite, and illite are the main minerals in the coal. Compared with the world’s low-rank coals, Ni, Co, Mo, and Ta are slightly enriched, Li, Rb, Cs, Ba, Tl, Bi, and Ge are depleted, and the concentrations of other trace elements are comparable to the average values of the world’s low-rank coals. The REY of the Dannanhu coals exhibited high fractionation, with its enrichment patterns characterized by the H-type and M-H-type. Although most of the critical metals are not enriched in the Dannanhu coals, the Ga, Zr (Hf), and Nb (Ta) concentrations in the coal ash of the Dannanhu coals have reached the economic cut-off grade and have the potential to be a substitute for rare metal resources. The terrigenous detrital sources of the Dannanhu coals mainly come from the Paleozoic dacite, andesite, and a small amount of granite from the Harik Mountain and Eastern Bogda Mountain in the Turpan-Hami Basin. The Dannanhu coals are generally in a dry and hot depositional environment, with high salinity and weak reduction-oxidation. The low source input and weak reduction-oxidation environment have resulted in low concentrations of critical metal of the No. 22 coal from the Dananhu Coal Mine.

Influence of Surface Chemistry on Metal Deposition Outcomes in Copper Selenide-Based Nanoheterostructure Synthesis.

The use of nanoparticle surface chemistry to direct metal deposition has been well-studied in the modification of metal nanoparticle substrates but is not yet well-established for metal chalcogenide particle substrates, although integration of these particles into nanoheterostructures is of high interest. In this report, we investigate the effect of Cu2-xSe surface chemistry on the morphology of metal deposition on these plasmonic semiconductor nanoparticles. Specifically, we functionalize Cu2-xSe nanoparticles with a suite of 12 different ligands and investigate how different aspects of the ligand structure do or do not impact the morphology and extent of subsequent metal deposition on the Cu2-xSe surface. Surprisingly, our results indicate that the morphology of the resulting metal deposits and the extent of metal deposition onto the existing Cu2-xSe particle substrate are indistinguishable for the majority of ligands tested. An exception to these findings is observed for particles functionalized by quaternary alkylammonium bromides, which exhibit statistically distinct metal deposition patterns compared to all other ligands tested. We hypothesize that this unique behavior is due to a cooperative binding mechanism of the quaternary alkylammonium bromides to the surface of copper selenide. Taken together, these results yield both new strategies for controlling postsynthetic modification of copper selenide nanoparticles and also reveal limitations of surface chemistry-based approaches for this system.