This is the code for commnad button in the Visualforce page.
<apex:commandButton
action="{!searchEmps}"
styleClass="slds-button slds-button_brand slds-button__icon"
Value="SEARCH" >
<svg class="slds-button__icon"
aria-hidden="true">
<use xlink:href="{!URLFOR($Resource.SLDS,'/SLDS_Icons/utility-sprite/svg/symbols.svg#search')}">
</use>
</svg>
</apex:commandButton>