Exhibit 4.1


 


SPECIMEN UNIT CERTIFICATE


 


NUMBER UNITS


 


U-


 


Power & Digital Infrastructure Acquisition
II 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 II 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 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 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               , 2022, 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


 




    2


     

    

 


Power & Digital Infrastructure Acquisition
II 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.


 




    3


     

    

 


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 allow redemption in connection with its initial business combination or to redeem
100% of the Common Stock if the Company has not consummated an initial business combination within 18 months (or 21 months or 24 months,
as applicable) from the closing of the initial public offering or (b) with respect to any other provisions of the amended and restated
certificate of incorporation relating to stockholders’ rights or pre-initial business combination activity, the holder of Common
Stock shall be provided with the opportunity to redeem their shares of Common Stock upon the approval of any such amendment, at a per-share
price, payable in cash, equal to the aggregate amount then on deposit in the trust account, including interest not previously released
to the Company to pay taxes, divided by the number of then outstanding shares of 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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