Green Hydrogen and the Anion Exchange Membrane Water Electrolyzer

The Molecular Nightclub

Imagine a bustling nightclub. This is your electrolytic cell. Outside, you have a long line of groups trying to get in. These groups are water molecules (H₂O)—two hydrogen atoms holding hands with one oxygen atom. Your goal is to break up these groups to get the VIPs: pure Hydrogen.

In this club, the dance floor is governed by electricity. But you cannot simply zap the water and hope for the best. You need a system to manage the crowd. If you do not manage the traffic, the club gets too crowded and shuts down.

This is where the Anion Exchange Membrane Water Electrolyzer (AEMWE) comes in. It is the specific architecture of the club that keeps the party moving.

How the Anion Exchange Membrane Water Electrolyzer Works

The process happens at the door, known as the cathode. Here, a catalyst acts like a bouncer. It grabs a water molecule and splits it up. The two Hydrogen atoms pair up and leave as gas—this is the fuel we want. But we are left with a straggler: a Hydroxide ion (OH^-). This ion is negatively charged, or an ‘anion’.

If these anions pile up, the reaction stops. They need to leave. The AEMWE features a special velvet rope—the Anion Exchange Membrane. It is a selective barrier. If you are a positively charged ion, you are blocked. If you are a negatively charged anion (OH^-), then you are allowed to pass through the membrane to the other side of the room (the anode). This flow of ions completes the electrical circuit.

Step-by-step, the mechanism flows like this:

1. The Split: Electricity hits the cathode catalyst, breaking water into H₂ and OH^-.
2. The Exit: Hydrogen gas bubbles away immediately.
3. The Migration: The OH^- anions travel through the membrane.
4. The Balance: At the anode, these anions are turned into oxygen and water, releasing electrons to keep the power flowing.

The Nickel Bouncer

For years, the best ‘bouncer’ for this job has been platinum. It is efficient and fast. It is also incredibly expensive. You cannot build a global energy infrastructure if your bouncers charge celebrity rates.

This review focuses on Nickel. Nickel is the local, affordable alternative. It is cheap and abundant. However, Nickel can be lazy. It sometimes lacks conductivity or degrades after a long shift, oxidising and losing its ability to split water effectively.

The paper analyses strategies to ‘train’ Nickel. By mixing it with other metals (alloying) or structuring it into nanosheets, scientists can boost its stamina. The review suggests that tuning the electronic structure of Nickel—essentially changing how it interacts with the water molecules—can make it perform nearly as well as noble metals. If we can perfect these Nickel-based catalysts, then the cost of green hydrogen could drop significantly, making the AEMWE a viable competitor to fossil fuels.