In an effort to decrease the high cost associated with the design, testing, and production of electrocatalysts, a completely electrochemical scheme has been developed to deposit and platinize a nanoporous Au (NPG) based catalyst for formic acid oxidation. The proposed route enables synthesis of an alternative to the most established, nanoparticles based catalysts and addresses issues of the latter associated with either contamination inherent from the synthetic route or poor adhesion to the supporting electrode. The synthetic protocol includes as a first step, electrochemical codeposition of a Au((1-x))Ag(x) alloy in a thiosulfate based electrolyte followed by selective electrochemical dissolution (dealloying) of Ag as the less noble metal, that generates an ultrathin and preferably continuous porous structure featuring thickness of less than 20 nm. NPG is then functionalized with Pt (no thicker than 1 nm) by surface limited redox replacement (SLRR) of underpotentially deposited Pb layer to form Pt-NPG. SLRR ensures complete coverage of the surface with Pt, believed to spread evenly over the NPG matrix. Testing of the catalyst at a proof-of-concept level demonstrates its high catalytic activity toward formic acid oxidation. Current densities of 40-50 mA cm(-2) and mass activities of 1-3 A.mg(-1) (of combined Pt-Au catalyst) have been observed and the Pt-NPG thin films have lasted over 2600 cycles in standard formic acid oxidation testing.

This article reports the results of a curriculum survey of 322 analytical chemistry instructors (92% U.S.-based) conducted during Spring 2021. This snapshot of current course formats, topics, and pedagogical methods will be useful to both seasoned and novice teachers of analytical chemistry. The majority of respondents reported that their major requires two analytical chemistry courses, and 97% of respondents reported that at least one analytical course is required. Over 80% reported a required analytical lab course. The topic rated most important was standardization and calibration methods, followed by UV−vis absorbance spectroscopy, data handling, HPLC, GC, statistical analysis, general chromatographic theory, sources and types of error, mass spectrometry, and acid−base theory/ equilibria/buffers. In general, topics that were rated as important were likely to be taught in required courses and addressed in hands-on laboratories. Over 80% of instructors reported the use of at least one evidence-based active learning strategy.In response to openended questions, instructors shared their strategies for student career preparation, project-based learning, and inclusive teaching, with these responses summarized using thematic analysis. Responses from 117 instructors give a snapshot of current efforts to promote diversity, equity, and inclusion, including cultivation of an inclusive environment, implementation of active learning, and examples of diverse scientists and culturally relevant examples. Respondents also reported the biggest challenge to their teaching, which was most frequently associated with obtaining and maintaining instrumentation. The results of this survey will help inform curricular updates in individual courses and programs and may inspire larger community-wide efforts to improve undergraduate analytical instruction.

Nanopores are promising structures for small-volume separations, but they often require complex top-down fabrication and are not easily (re)­configurable to allow for dynamically tuned separations. Herein we report the first use of nanoporous gold (NPG) membranes as tunable, charge-based separation elements. NPG is fabricated into a robust network of interconnecting pores via simple solution de-alloying. We demonstrate that control over the selective permeation of small-molecule analytes can be controlled via three different methods: (1) anion adsorption at the Au surface; (2) pH-tuning of self-assembled monolayer (SAM) charge; and (3) electrochemical oxidation of a redox-active SAM. This simple and versatile membrane system is promising as a dynamically tunable element for small-volume separations.

Nanopores, and nanoporous materials in general, are interesting for applications in chemical and biomolecular transport as pore sizes are on the same scale as the dimension of many (bio)chemical species. Many studies have focused on either single pores or small arrays of cylindrical pores, which are convenient in terms of their amenability toward computational modeling of transport phenomenon. However, the limited overall porosity may inhibit transport flux as well as the eventual implementation of these materials as active separation elements. Inspired by its relatively high porosity, we have explored nanoporous gold (NPG) as a membrane across which small molecular species can be transported. NPG offers a random, bicontinuous pore geometry, while also being inherently conductive and readily amenable to surface modification-attributes that may be enabling in the pursuit of size- and charge-based approaches to molecular separations. NPG was fabricated via a free-corrosion process whereby immersion of Au-containing alloys in concentrated nitric acid preferentially dissolves the less noble metals (e.g., Ni, Cu). Average pore diameters of 50 ± 20 nm were obtained as verified under scanning electron microscopy. NPG membranes were sandwiched between two reservoirs, and the selective transport of chemical species across the membrane in the presence of an ionic strength gradient was investigated. The flux of small molecules were monitored by UV-vis absorption spectrometry and found to be dependent upon the direction and magnitude of the ionic strength gradient. Moreover, transport trends underscored the effects of surface charge in a confined environment, considering that the pore diameters were on the same scale as the electrical double layer experienced by molecules transiting the membrane. Under such conditions, the transport of anions and cations through NPG was found to depend on an induced electric field as well as ion advection. Further electrical and surface chemical modulations of transport are expected to engender increased membrane functionality.