Scientists develop energy-efficient hydrogen production by urea electrolysis

• Indian Scientists have designed an electrocatalyst system for energy-efficient hydrogen production with the help of electrolysis of urea.

Urea Electrolysis

• A new technology has been developed that accomplishes the direct conversion of urine and urea to pure hydrogen via electrochemical oxidation with an inexpensive nickel catalyst.
• The urea electrolysis is helpful towards urea-based waste treatment with low-cost hydrogen production.
• The energy-intensive counterpart of water splitting, oxygen evolution, can be replaced with urea oxidation in urea electrolysis.
• The main challenge associated with urea oxidation is retaining the prolonged activity of the catalyst as the strong adsorption of the reactive intermediate (COx) on the active site, referred to as catalyst poisoning, causes activity loss.

The Research

• Center for Nano and Soft Matter Sciences (CeNS) have developed a Nickel oxide (NiOx) based system for producing hydrogen from electro-oxidation of urea.
• Scientists have explored electrocatalysts and shown that surface defective NiO and Ni2O3 systems having more Ni3+ ions are more efficient electrocatalysts than conventional NiO.
• They have used high-energy electron beams to produce surface defective unsaturated Ni sites in NiO (e-NiO).
• The study reveals that e-NiO prefers direct mechanisms of urea electro-oxidation due to strong adsorption of urea molecules, whereas NiO favors indirect mechanisms with low activity.
• The prominent electrocatalyst poison COx could be removed by adjusting the molar ratio of KOH and Urea with improved kinetics.
• Some researchers are of the opinion that the e-beam treatment is an effective way to produce a large number of coordinatively unsaturated active sites on electrocatalysts.
• It was observed that these generated sites effectively adsorb urea and favors direct urea electro-oxidation mechanisms (UOR).
• The researcher continued the studies on another Ni3+ oxide system (Ni2O3), revealing that active species Ni3+O(OH) on Ni2O3 possess higher COx tolerance than NiO.
• The active species of high valent Ni oxide system has a profound effect on catalyst activity.

Benefits

• The energy requirement for production of hydrogen through water electrolysis can be reduced by 70 % through urea electrolysis.
• Urea-based waste treatment with low-cost hydrogen production can be utilized for energy production towards our country's benefits.
• The low-cost, earth-abundant Ni-based catalysts are widely applied for this process.

Conclusion

• The urea electrolysis is helpful towards urea-based waste treatment with low-cost hydrogen production.
• India is one of the top countries by urea production and produced 244.55 LMT of urea during 2019-20.
• The nitrogenous fertilizer industries generate a high concentration of ammonia and urea as effluents.
• This can be utilized for energy production towards our country's benefits.