Exhibit 10.6


 


THIS
PROMISSORY NOTE (“NOTE”) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”).
THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE
THEREOF UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM, SCOPE AND SUBSTANCE TO THE COMPANY THAT SUCH
REGISTRATION IS NOT REQUIRED.


 


PROMISSORY
NOTE


 


	Principal
    Amount: $300,000	  Dated
    as of April 28, 2021


 


TKB
Critical Technologies 1, a Cayman Islands exempted company (the “Maker”), promises to pay to the order of TKB Sponsor
I, LLC, a Delaware limited liability company, or its registered assigns or successors in interest (the “Payee”), or
order, the principal sum of Three Hundred Thousand Dollars ($300,000) or such lesser amount as shall have been advanced to Payee to Maker
and shall remain unpaid under this Note on the Maturity Date (as defined below) in lawful money of the United States of America, on the
terms and conditions described below. All payments on this Note shall be made by check or wire transfer of immediately available funds
or as otherwise determined by the Maker to such account as the Payee may from time to time designate by written notice in accordance
with the provisions of this Note.


 


1.
Principal. The entire unpaid principal balance of this Note shall be payable on the earlier of: (i) December 31, 2021 or (ii)
the date on which Maker consummates an initial public offering of its securities (such earlier date, the “Maturity Date”).
The principal balance may be prepaid at any time. Under no circumstances shall any individual, including but not limited to any officer,
director, employee or stockholder of the Maker, be obligated personally for any obligations or liabilities of the Maker hereunder.


 


2.
Drawdown Requests. Maker and Payee agree that Maker may request, from time to time, up to Three Hundred Thousand Dollars ($300,000)
in drawdowns under this Note to be used for costs and expenses related to Maker’s formation and the proposed initial public offering
of its securities (the “IPO”). Principal of this Note may be drawn down from time to time prior to the Maturity Date
upon written request from Maker to Payee (each, a “Drawdown Request”). Each Drawdown Request must state the amount
to be drawn down, and must not be an amount less than Ten Thousand Dollars ($10,000) unless otherwise acceptable to Payee. Payee shall
fund each Drawdown Request no later than three (3) business days after receipt of a Drawdown Request; provided, however, that the maximum
amount of drawdowns outstanding under this Note at any time may not exceed Three Hundred Thousand Dollars ($300,000). No fees, payments
or other amounts shall be due to Payee in connection with, or as a result of, any Drawdown Request by Maker.


 


3.
Interest. No interest shall accrue on the unpaid principal balance of this Note.


 


4. Application
of Payments. All payments shall be applied first to payment in full of any costs incurred in the collection of any sum due under
this Note, including (without limitation) reasonable attorney’s fees, then to the payment in full of any late charges and
finally to the reduction of the unpaid principal balance of this Note.


 






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5.
Events of Default. The following shall constitute an event of default (“Event of Default”):


 


(a)
Failure to Make Required Payments. Failure by Maker to pay the principal amount due pursuant to this Note within five (5) business
days of the date specified above.


 


(b)
Voluntary Bankruptcy, Etc. The commencement by Maker of a voluntary case under any applicable bankruptcy, insolvency, reorganization,
rehabilitation or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee,
trustee, custodian, sequestrator (or other similar official) of Maker or for any substantial part of its property, or the making by it
of any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the taking
of corporate action by Maker in furtherance of any of the foregoing.


 


(c)
Involuntary Bankruptcy, Etc. The entry of a decree or order for relief by a court having jurisdiction in the premises in respect
of Maker in an involuntary case under any applicable bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator,
assignee, custodian, trustee, sequestrator (or similar official) of Maker or for any substantial part of its property, or ordering the
winding-up or liquidation of its affairs, and the continuance of any such decree or order unstayed and in effect for a period of sixty
(60) consecutive days.


 


6.
Remedies.


 


(a)
Upon the occurrence of an Event of Default specified in Section 4(a) hereof, Payee may, by written notice to Maker, declare this Note
to be due immediately and payable, whereupon the unpaid principal amount of this Note, and all other amounts payable hereunder, shall
become immediately due and payable without presentment, demand, protest or other notice of any kind, all of which are hereby expressly
waived, anything contained herein or in the documents evidencing the same to the contrary notwithstanding.


 


(b)
Upon the occurrence of an Event of Default specified in Sections 5(b) or 5(c), the unpaid principal balance of this Note, and all other
sums payable with regard to this Note, shall automatically and immediately become due and payable, in all cases without any action on
the part of Payee.


 


7. Waivers. Maker
and all endorsers and guarantors of, and sureties for, this Note waive presentment for payment, demand, notice of dishonor, protest,
and notice of protest with regard to the Note, all errors, defects and imperfections in any proceedings instituted by Payee under
the terms of this Note, and all benefits that might accrue to Maker by virtue of any present or future laws exempting any property,
real or personal, or any part of the proceeds arising from any sale of any such property, from attachment, levy or sale under
execution, or providing for any stay of execution, exemption from civil process, or extension of time for payment; and Maker agrees
that any real estate that may be levied upon pursuant to a judgment obtained by virtue hereof or any writ of execution issued
hereon, may be sold upon any such writ in whole or in part in any order desired by Payee.


 






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8.
Unconditional Liability. Maker hereby waives all notices in connection with the delivery, acceptance, performance, default, or
enforcement of the payment of this Note, and agrees that its liability shall be unconditional, without regard to the liability of any
other party, and shall not be affected in any manner by any indulgence, extension of time, renewal, waiver or modification granted or
consented to by Payee, and consents to any and all extensions of time, renewals, waivers, or modifications that may be granted by Payee
with respect to the payment or other provisions of this Note, and agrees that additional makers, endorsers, guarantors, or sureties may
become parties hereto without notice to Maker or affecting Maker’s liability hereunder.


 


9.
Notices. All notices, statements or other documents which are required or contemplated by this Note shall be: (i) in writing and
delivered personally or sent by first class registered or certified mail, overnight courier service or facsimile or electronic transmission
to the address designated in writing, (ii) by facsimile to the number most recently provided to such party or such other address or fax
number as may be designated in writing by such party and (iii) by electronic mail, to the electronic mail address most recently provided
to such party or such other electronic mail address as may be designated in writing by such party. Any notice or other communication
so transmitted shall be deemed to have been given on the day of delivery, if delivered personally, on the business day following receipt
of written confirmation, if sent by facsimile or electronic transmission, one (1) business day after delivery to an overnight courier
service or five (5) days after mailing if sent by mail.


 


10.
Construction. THIS NOTE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF NEW YORK, WITHOUT REGARD TO CONFLICT OF
LAW PROVISIONS THEREOF.


 


11.
Severability. Any provision contained in this Note which is prohibited or unenforceable in any jurisdiction shall, as to such
jurisdiction, be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof,
and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable such provision in any other
jurisdiction.


 


12.
Trust Waiver. Notwithstanding anything herein to the contrary, the Payee hereby waives any and all right, title, interest or claim
of any kind (“Claim”) in or to any distribution of or from the trust account to be established in which the proceeds
of the IPO conducted by the Maker (including the deferred underwriters discounts and commissions) and the proceeds of the sale of the
warrants issued in a private placement to occur prior to the consummation of the IPO are to be deposited, as described in greater detail
in the registration statement and prospectus to be filed with the Securities and Exchange Commission in connection with the IPO, and
hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the trust account for any reason whatsoever.


 


13.
Amendment; Waiver. Any amendment hereto or waiver of any provision hereof may be made with, and only with, the written consent
of the Maker and the Payee.





 






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14.
Assignment. No assignment or transfer of this Note or any rights or obligations hereunder may be made by any party hereto (by
operation of law or otherwise) without the prior written consent of the other party hereto and any attempted assignment without the required
consent shall be void.


 


[Signature
page follows]





 






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IN
WITNESS WHEREOF, Maker, intending to be legally bound hereby, has caused this Note to be duly executed by the undersigned as of the
day and year first above written.


 


	 	TKB CRITICAL TECHNOLOGIES 1 
	 	 	 
	 	By:	/s/
    Greg Klein
	 	 	Name:
    Greg Klein
	 	 	Title:  Co-Chief
    Executive Officer


 






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