Exhibit 4.1


 


SPECIMEN UNIT CERTIFICATE


 


NUMBER UNITS


 


U-


 


Power & Digital Infrastructure
Acquisition Corp.


 


SEE REVERSE FOR CERTAIN DEFINITIONS


 


CUSIP


 


UNITS CONSISTING
OF ONE SHARE OF COMMON STOCK AND ONE-HALF OF ONE REDEEMABLE

WARRANT TO PURCHASE ONE SHARE OF CLASS A COMMON STOCK


 


THIS CERTIFIES THAT


 


is the owner of               Units.


 


Each Unit (“Unit”) consists of one (1) share of
Class A common stock, par value $0.0001 per share (“Common Stock”), of Power & Digital Infrastructure Acquisition
Corp., a Delaware corporation (the “Company”), and one-half (1/2) of one redeemable warrant (each whole warrant, a
“Warrant”). Each whole Warrant entitles the holder to purchase one (1) share (subject to adjustment) of Common Stock
for $11.50 per share (subject to adjustment). Each Warrant will become exercisable on the later of (i) thirty (30) days after the
Company’s completion of a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or other similar
business combination with one or more businesses (each a “Business Combination”), and (ii) twelve (12) months from
the closing of the Company’s initial public offering, and will expire unless exercised before 5:00 p.m., New York City time,
on the date that is five (5) years after the date on which the Company completes its initial Business Combination, or earlier upon
redemption or liquidation (the “Expiration Date”). The Common Stock and Warrants comprising the Units represented by
this certificate are not transferable separately prior to                 , 2021, unless Barclays Capital Inc. and BofA Securities, Inc. elect
to allow earlier separate trading, subject to the Company’s filing with the Securities and Exchange Commission of a Current
Report on Form 8-K containing an audited balance sheet reflecting the Company’s receipt of the gross proceeds of the initial
public offering and issuing a press release announcing when separate trading will begin. No fractional warrants will be issued
upon separation of the Units and only whole Warrants will trade. The terms of the Warrants are governed by a Warrant Agreement,
dated as of                , 2021, between the Company
and Continental Stock Transfer & Trust Company, as Warrant Agent, and are subject to the terms and provisions contained therein,
all of which terms and provisions the holder of this certificate consents to by acceptance hereof. Copies of the Warrant Agreement
are on file at the office of the Warrant Agent at 1 State Street, 30th Floor, New York, New York 10004, and are available to any
Warrant holder on written request and without cost.


 


This certificate shall be governed by and construed in accordance
with the internal laws of the State of New York.


 


Witness the facsimile signatures of its duly authorized officers.


 





	By:	 	 
	 	Chief Financial Officer	 



 




     


     


    

 


Power & Digital Infrastructure
Acquisition Corp.


 


The Company will furnish without charge
to each unitholder who so requests, a statement of the powers, designations, preferences and relative, participating, optional
or other special rights of each class of stock or series thereof of the Company and the qualifications, limitations, or restrictions
of such preferences and/or rights.


 


The following abbreviations, when used in
the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable
laws or regulations:


 





	TEN COM	—	as tenants in common	UNIF GIFT MIN ACT —	 	 	 	Custodian	 	 
	 	 	 	 	 	(Cust)	 	 	 	(Minor)


 


	TEN ENT	—	as tenants by the entireties	under Uniform Gifts to Minors Act
	 	 	 	(State)


 


	JT TEN	—	as joint tenants with 
	 	 	right of survivorship and 
	 	 	not as tenants in 
	 	 	common


  


Additional abbreviations may also be used though not in the
above list.


 




    2


     


    

 


For value received, hereby sells, assigns and transfers
unto


 


PLEASE INSERT SOCIAL SECURITY OR

OTHER IDENTIFYING NUMBER OF

ASSIGNEE


 


(PLEASE PRINT OR TYPEWRITE NAME AND
ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)


 


Units represented by the within Certificate, and do hereby irrevocably
constitute and appoint Attorney to transfer the said Units on the books of the within named Company with full power of substitution
in the premises.


 





	Dated 	 	 	 
	 	 	 	 
	 	 	 	 
	 	 	 	Notice: The signature to this assignment must correspond with the name as written upon the face of the certificate
    in every particular, without alteration or enlargement or any change whatever.



 


	Signature(s) Guaranteed:	 
	 	 
	 	 
	THE SIGNATURE(S) MUST BE GUARANTEED BY
                                 AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP
                                 IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15 OR ANY SUCCESSOR
                                 RULES).


	 






 





In each case, as more fully described in the Company’s
final prospectus dated , 2021, the holder(s) of this certificate shall be entitled to receive a pro-rata portion of certain funds
held in the trust account established in connection with the Company’s initial public offering only in the event that (i)
the Company redeems the shares of Common Stock sold in its initial public offering and liquidates because it does not consummate
an initial business combination by the date set forth in the Company’s amended and restated certificate of incorporation,
(ii) the Company redeems the shares of Common Stock sold in its initial public offering in connection with a stockholder vote to
amend the Company’s amended and restated certificate of incorporation (a) to modify the substance or timing of the Company’s
obligation to provide holders of shares of Class A common stock the right to have their shares redeemed in connection with the
Company’s initial business combination or to redeem 100% of the Common Stock if it does not consummate an initial business
combination by the date set forth in the Company’s amended and restated certificate of incorporation or (b) with respect
to any other provisions relating to the rights of holders of holders of Class A Common Stock or (iii) if the holder(s) seek(s)
to redeem for cash his, her or its respective shares of Common Stock in connection with a tender offer (or proxy solicitation,
solely in the event the Company seeks stockholder approval of the proposed initial business combination) setting forth the details
of a proposed initial business combination. In no other circumstances shall the holder(s) have any right or interest of any kind
in or to the trust account.


 


 


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