> For the complete documentation index, see [llms.txt](https://mit-energy-hardware-bench.gitbook.io/ehb-mit/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mit-energy-hardware-bench.gitbook.io/ehb-mit/documentation/readme.md). # Projects ### Online Quantitative Mass Spectrometry Operando mass spectrometry can be used to continuously monitor and quantify the volatile products produced by a chemical or electrochemical reaction making it both a powerful diagnostic and scientific tool. **QU**antatative **A**naly**S**is of vol**A**tiles via **R**eal-time **M**ass **S**pectrometry **(QUASAR-MS),** is an open-source, sensitive, repeatable, and low-cost online mass spectrometry system where both the instrument's software and hardware can be reconfigured to an experiment's specific needs. We strongly believe that an open source community can lower the entry and cost barriers to using *operando* quantitative gas analysis systems while extend the technique to a wide range of industrial-grade electrolytes to help bridge the all too common valley-of-death in energy research.

System diagram of QUASAR's open source quantitative mass spectrometry system.

**QUASAR's** hardware is designed to be easily maintain-able by researchers with parts being selected for both their availability and replaceability without the need for precise alignment. The system is designed to be resistant to industrial-grade electrolytes such as potassium hydroxide and sulfuric acid at high concentrations (>5M), though reconfiguration of specific parts may be required depending on the user's choice of electrolyte. The documentation on this website contains a (1) theory of operation, (2) a list of parts and assembly instructions, (3) calibration procedures and data, (4) required software, and (5) tips and tricks to modify the system to your experimental needs. We also maintain an updated list of experiments that have used the platform or variants of the platform as a starting point for your own work. #### Applications of QUASAR Below are example experiments that have been performed with Quadrupole and its adaptations. * Quantification of the efficiency of hydrogen production from both alkaline-water electrolysis (AWE) and chemical-based reactors; measurement of Faraday and Energy Efficiency (kWh/kg) under quasi-industrial conditions (30wt% KOH @ 25°C). * Measurement of gas crossover and efficiency loss mechanisms in water electrolysis including comparative studies on membrane, separator, and seperator-less technologies. * High-througput screening of parameters for pulsed electrolysis with applications in water-splitting, direct waste water to hydrogen production, CO2 reduction, and critical minerals recovery. * Characterization of aqueous metal-air batteries (AMABs) with gas-diffusion cathodes. ### Electrochemical Test Cells The design of electrochemical test cells has significant effects on the quality of experimental data; a well-documented starting cell can significantly reduce debugging time especially in the early stages of research. In addition to this, the translatability of electrochemical cells between different *operando* and *in-situ* characterization methods is non-trivial and often requires significant engineering effort or additional characterization to be able to replicate conditions across multiple techniques. On this website, we provide documentation for two key types of test cells. The first type, are standard H-Cells that are designed to couple directly with **QUASAR** while simultaneously being compatible with optical characterization equipment such as high-speed cameras, Raman Spectrometers, and IR Spectrometers. The second type are half-cells that similarly couple with **QUASAR** but are designed for *operando* XAS characterization at the beamline. All cells are designed for compatability with industrial-grade electrolytes (30wt% KOH @ 25°C), include the option to add a reference electrode, and can be operated both as flow-cells or stand-alone. In addition to cell design, manufacturing, and assembly instructions, we've included detailed characterization data for each of these cells. This data includes CV and EIS curves, polarization curves, faraday efficiency measurements, overpotential plots, efficiency curves, ex-situ XPS data, *operando* XAS data, mass spectrometer pressures and flow rates from **QUASAR**, and preparation and experimental procedures. {% columns %} {% column %}
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{% endcolumn %} {% endcolumns %} ### Resources Additional resources are provided on this website for characterization techniques including *operando* Mass Spectrometry, ex-situ X-Ray Photoelectron Spectroscopy (XPS) and Grazing-Incidence X-Ray Diffraction (GI-XRD), *operando* X-Ray Absorption Spectroscopy (XAS), Electrochemical Impedance Spectroscopy (EIS), and other references we've found useful in our work. Please visit the resources page and email us at with suggested additions. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://mit-energy-hardware-bench.gitbook.io/ehb-mit/documentation/readme.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.