👁️🗨️ Simple Chemical Hydrogen Production — Step-by-Step (Magnesium Route)
Distilled build notes and concepts for magnesium + saltwater/vinegar systems producing electricity and hydrogen.
1) Air-breathing Mg–Saltwater Cell (Baseline) battery & slow H₂
What it is: A simple magnesium–air “battery” that also slowly makes hydrogen.
- Parts: Magnesium plate/strip (anode), steel wool or carbon felt (air-breathing cathode), saltwater (electrolyte), simple enclosure.
- Build: Place Mg opposite the air-breathing cathode; add saltwater.
- Output (demo scale): ~1.3–1.5 V, ~0.1 A (crude) up to ~1 A (improved), runs ~24 h until Mg passivates.
- Maintenance: Scrub off the white byproduct (mostly Mg(OH)2/Mg salts) and reinsert; replace Mg when thin.
2) “Sandwich” Cell (Compact, More Efficient)
What changes: Reduce electrode spacing and add a thin polymer electrolyte layer.
- Stack: Air-side mesh/cage → carbon felt → thin PEM/ionomer fiber (optional but boosts reaction) → saltwater gap → Mg plate in a snug housing.
- Result: ≈ 1.5 V at ~1 A for ~24 h on a small Mg plate (≈ “near a watt”), with easy plate swap/clean.
3) Hybrid Power + Hydrogen (Vinegar Assist) dual-output
Goal: Make extra H₂ chemically while the Mg–air cell makes electricity.
- Electrolyte: Saltwater + diluted vinegar (acetic acid) to accelerate H₂ without runaway heat.
- Plumbing: Add a gas outlet to route H₂ to a separate single PEM fuel cell.
- Outputs:
- Mg–air section: ~1.5 V (~1 A).
- H₂ → PEM fuel cell: another ~1.5 V (independent).
- Tradeoff: Faster Mg consumption (≈ half-day per plate), but you get electricity + hydrogen concurrently.
4) Dedicated Chemical H₂ Generator → Fuel-Cell Stack best run-time
- Reactor: Put Mg flakes in a bottom chamber; add diluted vinegar. Gas rises into an accumulator/wash, then on to the fuel-cell stack.
- Fuel-cell stack output: Ramps from ~6 V up toward ~10–12 V as H₂ saturates (enough to light small 12 V bulbs near 12 V).
- Run: Continues for many hours (“all day”) on a few Mg flakes; add more when it slows.
5) Chemistry in One Glance
- Mg–air cell (saltwater + O₂): Mg → Mg²⁺ + 2e⁻ (anode), O₂ + 2H₂O + 4e⁻ → 4OH⁻ (cathode). Slow H₂ may form on Mg via water reduction.
- Vinegar boost (acid route): Mg + 2H⁺ → Mg²⁺ + H₂↑ (fast fizz = hydrogen).
- Reality check: Magnesium is the fuel. You’re converting Mg’s chemical energy into electricity/H₂.
6) Safety Essentials (Don’t Skip)
- Ventilation: Hydrogen is flammable/explosive; no sparks/flames.
- Dilute acids: Start weak; reaction can get hot.
- Never seal gas tight: Provide pressure relief; use check valves and a bubbler/wash bottle.
- Byproducts: Mostly magnesium hydroxide/salts; avoid ingestion; handle and dispose responsibly.
- Electrical: Prevent shorts; keep moisture out of fuel-cell terminals.
7) Quick Upgrade Ideas (Speculative, Fun)
- Surface area: Use perforated/etched Mg or flakes to tune reaction rate.
- Depassivation: Small chloride content (salt) helps limit MgOH skin; periodic mechanical agitation helps.
- Cathode doping: Manganese or Fe–N–C catalysts on carbon felt can improve O₂ reduction.
- Membrane tweak: Thin PEM/ionomer fiber layer to stabilize ionic paths.
- Gas conditioning: Simple dryer/wash (e.g., silica gel / NaHCO₃ wash) for cleaner H₂ to the PEM stack.
- Pulsed loads: Use the stack to drive a low-power pulser for experiments with electrolyzers or charge pumps.
